You can play in NTRP tournaments without an NTRP rating, which is what you'll have to do if you can't self rate. It's not uncommon - about half of the guys I've played in tournaments at the 3.5 level show up in TennisLink as "Not Rated".
There are no dynamic disqualification rules in tournament play and the early start ratings are based solely on league play, so assuming you don't join a league you won't be assigned a computer rating until the end of the year.
All of the NTRP silliness (DQ's, early start ratings, etc) you read about on the forums has to do with league play. If all you do is play tournaments the only time your NTRP rating will change is at the end of the year.