FLEX can never be below climb thust (due to performance requirements) therefore you are always in the (TOGA) limit region during takeoff.....Hence the stop watch start!
I fly CRJs, and the -200s are usually flexed down to 85% N1, and reaching acceleration altitude you ask for flapretraction and climb power, which will be around 90% N1.
After having flown an airbus for 10 years, that struck me as rather strange, but it is an approved and safe procedure...
Nic