I'm just finishing up my single engine land CPL, and my flight instructor has been kind of slacking lately and giving me assignments merely 1-2 hours before a flight rather than a day or two's notice, which i feel is more professional and quite frankly less stressful.
1-2 hours before a flight is a reasonable time frame, and a lot more than I remember having sometimes. Being texted the route the night before is more than you should be expecting (and more than you'll get on your test).
It does seem like a rush sometimes, especially at the beginning. My recommendation is to prepare and plan absolutely everything else you possibly can well in advance. If you're off blocks at 12, by 10am I would recommend being showered, dressed, at the airport, aircraft checked out (if on the ground) local notams checked, weather brief prepared etc etc. That way once you get your route your workload is minimized.
Getting used to that sort of time management will help you a lot, particularly with your IR (both on the ground and in the air).