I ALWAYS start my song at least four measures in to give me enough breathing room before I start playing (so a total of 8 measures with the metronome count in). If I'm comfortable enough and don't want to wait that long I'll just move the Now Time line closer. Then after I've finished the project I take the export and toss it into a new project for some polishing and move the stereo track closer to the start leaving a second or two of silence before the audio begins. Starting right on beat one cuts off any lead in noises and doesn't leave room for extra sounds I might want to add building up to the song. It's a lot easier than having to move umpteen tracks/clips at once to make room.
I've seen a lot of threads on here of people complaining or generally being befuddled about things that are easily solved by using this method. It's kind of weird actually. :-/