My insurance/tricare doesn't kick in until sep so my child will be almost 6mo by the time he gets his 4mo shots. is that alright?

Not totally: The immunization recommendation is meant to prevent illness. Thus your child may get away without getting ill by waiting. On the other hand, there is no way to predict that he won't get sick while waiting. The general advice is to follow the recommendation and perhaps call your insurer to see if they would make this exception since it may likely save it money which will be spent anyway.

Yes: Just let his pediatrician know and they can catch him up.

Should be : That should be fine although some entities are very solidly behind an arbitrary immunization schedule and that will put your little one behind on the schedule. Obviously if delayed the shots don't work until later so try to avoid exposing the little one to others that might be contagious with anything. Could pose increased risks with certain (especially foreign) travel. Try to stay on schedule