48 hour window. Or anytime after the month starts.

No. During the 48 hr window.

Picking up OT on RSV.

-48hr window.
-daily you can submit request.
-if you want to pick up OT for tomorrow then you can call before 8 am central or after 5 pm.
- you can also pick up OT via "reserve appropriation" at the last minute as long as you can get the flight out on time. If a reserve pilot has already been assigned a trip you can take that trip/part of the trip from him for premium pay. There are some restrictions. Look it up in the LOA.

On your last day of reserve, can they give you an overnight?

That would be known as a Junior Man. There can’t be any other pilot legal for trip and they can only do it to you twice a month and 12 times a calendar year.

Yes like the guy said above there are restrictions. They have to use reserve pilots airport standby even pilots at other airports have to assigned before they can give you a JM.

If it's a last minute event then they usually can't bring in an FO from a different airport or from home. Also they have to get you back as soon as possible. They can't put you in the hotel all day and work the late flight out when a legal earlier flight is available.

Or they can send you on a turn with a deadhead return that is oversold without any later flights. All those other requirements won't matter then.

You must tell them when your being junior manned for the second time in a month so they can put you on a special list. If you don’t then you can get a third

Do you have to do it the second time in the month or just the 12th time for the year?

Anyways after four year I have only had two junior mans.

Both.

As an FO I was jr manned maybe twice (other than due to wx). Since I upgraded early this year, I've been jr manner five times. YMMV.