Is this considered a vow that must be fulfilled, given the desire to delay the slaughter until financial conditions improve?

Undertaking a conditional vow (nadhr mu'allaq) is disliked, and it does not change anything from Allah's divine decree, based on the Prophet's (peace be upon him) saying: "Indeed, a vow does not bring about any good; it merely extracts [something] from a miserly person." However, a conditional vow must be fulfilled according to the manner in which its maker vowed it.

If the vow was merely a thought or an intention, then nothing is required from it, based on his (peace be upon him) saying: "Indeed, Allah has pardoned for my Ummah what they whisper to themselves, as long as they do not act upon it or speak about it."

Therefore, if what emanated from you was merely an intention or a thought, then nothing is required of you. However, if it was in the form of a vow, then it is binding upon you, and you must fulfill it when you are able.