How do I take provera and clomid? and how do I count the days for the 21 day blood work?

My doctor gave me 10 Provera and then 5 clomid, it says to take the clomid on days 5-9. Now my question is about the clomid, do i start taking it 5 days after my period starts? (say my period starts March 1st, would i count March 1,2,3,4 and on the 5th day take it?) or do i take them on the fifth day that i start my Provera?

ALSO they want me to come in for blood work on my 21st day, when do i start counting the 21 days?