Hi,
Do you mean consume the budget at the time of release and not on the creation? It won't be possible, due to prudence policy in PSM-FM. Imagine, creating a lot of PRs, which won't have effect at the budget and the lack or resources will be discovered only at their release.
Of course, by modifying standard code, in theory, you can force this kind of logic, but I won't recommend it both from technical and functional reasons.
Regards,
Eli