I, the Notary Public, accept / commit to complete the requirement in a timely fashion / in a timely manner...

sources:

Notarising Spanish Powers of Attorney – Thirsk Winton LLP
https://www.thirskwinton.co.uk/.../notarising-spanish-powers...
1 jun. 2014 - At Thirsk Winton LLP, we are well versed in the procedural requirements for a Spanish power to be properly notarised and legalised, ensuring it is readily accepted in Spain for its intended purpose, thereby ensuring that the transaction which it authorises can proceed in a timely fashion.


Why Legal Professionals Must Take The Notary Stamp Seriously | NNA
https://www.nationalnotary.org/notary.../legal-professionals...
11 sept. 2012 - The seal is such a key feature of notarization that the Notary Public Code ... Notary may be found to perform the notarization in a timely fashion.

Home - Seals On Wheels Mobile Notary Services
https://sealsonwheelsnotary.com/
spanish Home ... Mobile Notary in Los Angeles. ... that certified translations from Seals on Wheels will be accurate, accepted and provided in a timely manner.

State of Connecticut Notary Public Manual - CT.gov
https://portal.ct.gov/-/.../LegislativeServices/.../NotaryMa...
No matter what the reason, appointment as a notary public is a serious undertaking. The ..... Failure to return the renewal form in a timely manner could result in a lapse in the ..... For example, in many Spanish-speaking countries, the "notario.

Notary Public - Arkansas Secretary of State - Arkansas.gov
https://www.sos.arkansas.gov/uploads/bcs/NotaryHandbook.pdf
A notary public cannot notarize his/her own signature, or a document to which the notary is party, or a .... a timely manner. 4 ..... English and Spanish: “I am not a ...

--------------------------------------------------
Note added at 10 hrs (2019-02-08 21:01:11 GMT)
--------------------------------------------------

@Ruth

"oportuna diligencia" could be "proper notarial procedures" in your context:

I, the Notary Public, affirm that i will fulfill the notarization requirement in accordance with proper notarial procedures ...

sources:

Notary Tips on Best Practices - Notary Supplies
https://www.notarypublicstamps.com/articles/notary-best-prac...
It seems people feel that a notary public can do the same thing an attorney .... that the notarization was performed in accordance with proper notarial procedures.

Notary Public - Arkansas Secretary of State - Arkansas.gov
https://www.sos.arkansas.gov/uploads/bcs/NotaryHandbook.pdf
I affirm that I will fulfill these duties to the best of my ability and perform in accordance with the law and in the best interest of the corporation.” Signature of Person ...

...el requerimiento que cumplimentaré mediante la oportuna diligencia.
...I will comply with the due diligence requirement.
---------------------------------------------

Existe la frase "diligencia debida"/"debida diligencia" que es sinónimo de "oportuna diligencia" (due diligence / due care)

Por ejemplo:

Lawyers are sorting out for themselves how to revise their own practice procedures in terms of the amount of time they have to spend to get forms in order and how to comply ***with due diligence***.
https://www.osbar.org/publications/bulletin/06apr/bankruptcy...

Preparers must comply ***with due diligence*** requirements in determining eligibility for the credits and the amount of the credit.
http://news.cchgroup.com/2018/02/07/irs-reminds-preparers-du...

Further, Sections 20107a(6) and 21304c(6) specify utilities and severed mineral
right owners must comply ***with due care*** in regard to their own activities.
https://www.michigan.gov/documents/deq/deq-rrd-duecare-citiz...

In this context I don’t believe that “diligencia” refers to diligence, timely performance or procedures in general, but rather to a type of notarial instrument (additional context might indicate which type). Typical “diligencias notariales” include “protocolizaciones,” “autenticación de firmas,” “levantamiento de protestos,” “actas de donación,” “disolución de la sociedad de gananciales,” “requerimientos,” “apertura y publicación de testamentos cerrados”, etc. See many more types here:
https://www.slideshare.net/utplgestion/diligencias-notariale...

diligencia f.
Acta donde consta la forma y circunstancias en que se ejecuta un acuerdo o decisión judicial. Asímismo, hay diligencias notariales, en las que se hace constar en un documento ya preexistente una actuación posterior en el tiempo.
Ejemplo. Se otorga un acta notarial por la que se solicita del notario que haga un requerimiento a una persona. El notario lo hace al día siguiente de la fecha del acta. Esta actuación se refleja en el acta a continuación, por medio de una diligencia con la firma del notario.
http://glosario.notariado.org/?do=terms&letter=D

¿Cuántas clases de documentos notariales existen?
Los Documentos Notariales son, en principio, protocolares o extraprotocolares, según sus originales se extiendan en el protocolo o fuera de él. Los primeros consisten en escrituras públicas y actas notariales o protocolozaciones consignadas en el protocolo del notario. Los segundos son las reproducciones de Instrumentos Públicos, certificaciones de documentos, piezas de expedientes o inscripciones, traducciones, actas, diligencias y otras actuaciones que el Notario público, autorizado por ley, extiende fuera del protocolo.
http://guiasjuridicas.wolterskluwer.es/Content/Documento.asp...