With the rendezvous - Unlike holidays that's not set for one particular turn, that's just "we'll be waiting here UNTIL turn X" so yes, as soon as you get there, the meeting happens. It's got a few turns of wiggle room because it's completely unexpected, in-game, so she needs time to make it, but everyone wants to get it over with so once you're in position it will kick off.
You could park yourself the next sector over to prepare though!