The Church teaches that for "just reasons,"

Not exactly. Actually according to HV 16 specifically describing use of NFP, Paul VI teaches it is licit for "well grounded" reasons representing "reasonable" motives.

do you think that NFP is overused?"

To an extent, probably. To the extent you present it, no. "Open to life" does not mean "intending conception" nor strictly, requiring no use of family planning from day one of your marriage.

Yes we are called to trust in God, but nowhere is there a requirement to suspend our critical faculties and prudence in doing so, and procreation is a cooperation between spouses and God. You too strongly state your case.

Too many are willing to get right in the middle of the decision for procreation when the Church has carefully stayed out of it. Sobering thought that half of marriages that will fail will do so in 5 years. And during a time of a man adjusting to be a husband and a women a wife, in a world and time in history where this is no longer an indoctrinated state that children are groomed to, you seem to imply delaying birth with NFP is somehow 'not trusting God'. It's more I think about not trusting yourself and giving yourself the room to grow into your role.

There is some sort of misused theology out there that states, "God won't give you something you can't handle" as a justification for excusing caution from the decision process. Well, whether that is true or not is moot, and overcome by the plain fact that God gives people things they don't handle frequently. While you should be aggressive in following God and stretching your capability beyond what is comfortable. Keep a sure measure of the consequences of your own failings. And in the case of procreation they are quite dire. And open to life means that God can override your input on the matter if he desires. There is a balance, I've argued tooth and nail that a family using NFP to have only one child with no real reason other than "they got what they wanted out of having one child" was dead wrong. On the other hand I caution about being too aggressive with that line of thinking, the vast majority I think who use NFP and follow the Churches teachings are committed to life and family. And do wish to have more than 1.9 children. So my usual cut is you should plan to try for a minimum of 3 unless you have a pretty good reason to do otherwise.

For your own sake you should start as soon as you can. Delays are regretful.