Is it possible to make adjustments to the beatsync for the first measure without it affecting all the measures that follow?  Would I have to anchor every beat manually? I messed up and sync'd the whole song but the first couple measures are off and need to be corrected.. I'd like to avoid having to go back and re-adjust everything afterward if possible

Its a song with a fade in intro, bpm and time changes, and originally I just didn't worry about syncing the first measures properly bc there wasn't going to be any notes to play there yet while it fades in... but I changed my mind

Place an anchor on the beat where it begins being in sync.  Then you'll have to use some other means to manipulate the tempo map.  If there is any gap between the start of the song and the first beat, an easy option would be to use "Beat>Reset offset to zero", which will fill in that gap with one or more beats.  Then you can move any beat other than the first without affecting the rest of the tempo map that is already correct.  If the first beat already begins at the beginning of the song, then just leave it alone and move the other beat markers instead.  You can add or remove beats if you want via the Beat menu.

Thanks, that's exactly what I needed

I also used the "Move offset up" function after correcting to move the first beat back to the original place