From my experience a good sleeping pattern is very important for LDing, more specifically dream recall (which affects LDing a lot for obvious reasons).

Despite my experience making this clear, I find it's really hard to follow a good sleep pattern. I'm in university too so I know exactly what you're talking about... But I really really make an effort to at least go to sleep within 1 hour each night (so sometimes 23:00, sometimes 22:30, sometimes 23:30), and never break this rule if I can help it. Plus I try to keep it within a narrower range if possible.

My waking up hours fluctuate a lot more - I find that as long as I get 7 - 8 hours of total sleep I'm good to go. So if I start the day late I would, for example, wake up after 6 hours of sleep, have a large WBTB (while doing other stuff, like HW, eating, chores), and then sleep for up to 2 more hours. If I start the day early, I'll just shorten the WBTB as I have to to make the schedule work. In fact, most days I start fairly early, which is why I only have a couple of days per week where I can do a large WBTB. Factors like the chance to hit REM limit the max size of a WBTB to 2-3 hours, so if I start the day extra late (like in the afternoon), I still have to finish with sleep completely by 10:00 tops. If I start the day extra early - I rather have less sleep than get more sleep it in the afternoon or go to bed too early (this hurt my recall badly).

So to sum up my routine:
Going to bed time - keep as consistent as you can (very high priority).
Total sleep time - keep as consistent as you can (high priority).
Total time from going to sleep to final awakening - depending on schedule and WBTB limitations, but for me it's: [Total sleep time] < [] < [Total sleep time + 2 or 3 hours]