The latest you will get a call is about 2-3pm for a same say call. (if you start at 5am).
Basically, 2 hrs to get there, 1hr prior to flight, and the shortest leg is to PHL at 45min scheduled going there (if they just deadhead you for a next day flight,) and 30 min back.
So add it up, 2+1+1.25=4.25hrs
Subtract that from the end of your on call and you know when you're home free for a same day short callout.
With the # of reserves we have, add another hour or two because they have so many staggered on calls, they'd rather use a later one than push you to the end of a duty day. Trust me, I know this for a fact.

Like I said about going out in the city, pack a daybag, put it in the crew room or stuff it in your flight case, so the minute you get that call, hop on the subway and make your way to the airport.
Remember, on the subwaw to bus, you get dropped off in front of the terminal, no waiting for that cr@**y employee shuttle. I know you can do it, as I've made it out to the airport (area = buddy's crashpad) a few times in just over an hour from anywhere you can choose in manhattan.
Heck, hit up the beaches on long island and grab the LIRR back.

There's a lot you can do.

As to your agenda, you and me both man.
But the bottom line is that we can't do a lot about it, and when you hold a line, all you want is time off. Enjoy what you can get now.
As for open flying, there's not gonna be a lot over the fall and winter. We are pretty fat on reserves.
I've held a BU since I got here with the exception of one month. That one month of reserve (June), I only flew 8 days. I know another guy junior to me who only flew 2 days that month.
Even on BU lines, I only get scheduled for 6-9 days of work and get used maybe 1 max 2 rsv days for that month. It is what it is...