I think we had a recent thread on this exact same topic, but I can't remember what keywords would be best to search.

I would start your FHMs right now. They certainly won't mind lots of areas with shallow water.

I think(?) some of our experts also wanted BG early - provided your partially-filled pond had decent water clarity. Putting them in muddy water puts them at some risk, and they won't gain much weight or spawn much anyway.

Can you list your fish species that will be in your finished pond? That will help the actual experts give you some more solid advice on the timing.

If LMB are your top predator, are you planning on putting them in this fall, or next spring? Or is it dependent on getting enough rain this spring before you get the usual evaporative losses during the hottest parts of a Texas summer?