DWC answered the question but I'll do numbers (I'm on a PR day today) to translate from contract-ese/

I did a 2 Day GS that interrupted 1 X day. I blocked in at 2116 on the 20th.
Per the PWA, I am owed a full PB day for each X day interrupted for a GS / IA (it's different for late ops)
That PB day starts 9 hours after release.
S0, 2146 release on the 20th + 9 hours = 0646 on the 21st my 24 H starts. This gets confusing to some because the 21st shows PB on the schedule and PR on the 22nd.
My PR ends at 0646 on the 22nd.

IF the trip is on my schedule (protip, I go in icrew about this time and screen shot that schedule, it's the "real" not Micrew and has a to the second time stamp) 9 hours prior to the Partial ending (in this case, 2146 on the 21st) I can be assigned a trip or SC starting NET than end of PR+10 hours.
So, for today, they could have given me a trip or SC as long as it started 1646 or later, if it was on my schedule by 2146 last night. If nothing on schedule at 2147, the earliest you can report/start SC is end of PR + 12 hours, so in my case, 1846 tonight, since nothing was on my schedule last night by 2146.

That said, I did have to call CS and quote chapter and verse that GS/IA interrupting X day is relase plus 9, not to the minute like late ops.

Not an ALPA schedule guru, but have become fairly well versed in reserve rules. Feel free to PM me if you are worried about posting trips, release times, etc, and I can usually drive you to the relevcant PWA section/line/etc and who to call to fix it.

I once said the PWA might as well be written in Greek.. My wife went "I read greek and it confuses the hell out of me"