What should be included in a college application by the time you submit it?

I know what’s required in my college applications, but I’m wondering whether some documents can/should be sent after applying to colleges.

Could you complete and send a college application consisting of: Essays (of course), fee/fee waiver, letters of recommendation, etc. and then perhaps send your SAT/ACT test scores and high school transcript (9-11th grade) afterwards? Or would this all have to be included at once?

This is the one thing I’ve been quite confused about.

The stuff that you need to submit should be sent all at once. Things that are not sent by you (recs, transcripts, score reports) can be (and usually are) sent separately.