From 17 hours and 59 minutes down to 10 hours prior to report, you can be awarded a GS while on long call. This works because - it's too late for CS to call you out from long call (less than 18 hours to report, otherwise you could simply get it as a reserve assignment), but still enough time that you get 10 hours rest before report. It is awarded as F#1, F#2, etc as described above by Art. Once inside of 10 hours and still on LC you cannot do it. A REG pilot can accept the GS, because they are continuously on rest and will have the 10 hours by default.

You mentioned 30 hours. Doesn't sound like a 30/168 issue (without seeing your sked earlier this week). But you still need that 10 hours rest after the end of LC before you could accept a GS.

If today was your last LC day, you are automatically released at 0600 (if tomorrow is a golden X-day)
or
you may call CS at 0600 and ask to be released (if tomorrow is just a regular X-day).

If,
1) CS makes an error and does not automatically release you at 0600, or
2) you do not call and get released at 0600,

then your schedule will not show rest starting at 0600 and you will be illegal for GS until 1000 tomorrow.

To check your Reserve Rest, in iCrew:
Main Menu --> My Schedule --> press or click OK --> Display Reserve Rest Period Info (6th option down in the list)

On the following screen you should see 15JUN / xxxx (where xxxx is the time you were released, hopefully 0600 in this case)

At any rate, the earliest green you could work today would be a 1600 report. Beat feet for the fishing boat instead!