Newbie reserve question. I have read section 23 and still don't understand when I am eligible for long call or conversion to short call.

I have a trip from 28-31 March (OE). I have 6 days of reserve starting on 1 Apr. I was alerted today that I have been given a reserve rest period from the end of my rotation on the 31 (2038) to 2 Apr (0238) (30 hrs). Am I eligible for assignment at 0238 or am I eligible for 12 hr call out at 0238, meaning the earliest trip I can be assigned would be 1438 on the 2nd?

I'm happy to have the time off I just want to know what to expect. I also thought I read something about having to be notified by 1500 the day prior for any assignment. Does that mean 1500 on the 1st?

Thank in advance for the help.