Your employer 401k or 403b plan calculates your MRD each year.   The same calculation is done on your IRA accounts.   

Simple math, here's the calculation... they take your year end balance and divide by your life expectancy.  The calculation is approximately 4% of your account balance.  They do this calculation in January each year so you could call your your employer plan or IRA and request the funds now or wait until later this year.

 Probably makes sense to call and request your MRD amount!  You could send a check out or many plans will add your bank and send send electonically.  Pretty simple.