When's the due date for timetables etc
On your my.monash page, there should be a section detailed "important dates", filled with dates like this that you need. According to this section, preference entry ends on the 19th of Feb.
Also, reminder to those turning to MUTTS:
IF YOU HAVE LABS, YOU MUST BE ENROLLED IN THEM (also with 50% of tutes or so). If you're not enrolled in a lab, and get one you don't like, you MUST go to the one you don't like. The lab you're enrolled in is the lab you get marks for, and changing labs is not as easy as showing up to a tute and being all, "oh yeah, the tutor said I could come to this lab this week".
Particularly, most labs are hurdles (i.e., you must pass them to pass the unit), so you want to get a lab session you like. So, make sure you check allocate+ after enrollment so you can get the lab you want. If you have troubles logging into allocate+ on the lead-up to preference entry closing, contact Monash and get it sorted.