Ideas to help me hang prehung door please?

[shvl73]

What FWJ suggested is commonly done. Mistakes happen and adjustments are made, all the time.

 

[EddieWalker]

Update: I've taken one of the studs (jackpost?? I thought those were metal?) out.

You are working on the jack stud. It supports the header above and is attached to the king stud, which goes all the way up.

What you are doing is fine. Normally, time is money, so if a jack stud doesn't fit, 1x4's are used. I've seen plywood ripped to fit too. When replacing windows that need just a little more room, the sawzal is used.

Sounds like you have a good handle on it.

Eddie