The retention bonus goes in periods (jan-april, may-aug, sep-dec) and paid out the month after the period ends. If you are hired in the middle of one of these periods your retention bonus is pro-rated starting at your date of hire.

With regard to reserve that is the hard question to answer as you know I'm sure. With sustained movement you shouldnt be on reserve for too long, and thus far this year we have not had any major hiccups in hiring. All things considered though, past performance doesn't predict future results, as they say.