When should I start to test ovulatiin if I did not ovulate on day12 after an IVF failure.?

Depends on ur cycle. Your infertility doctor can advise you. You usually will ovulate 14 days before your next period. Subtract 14 from the length of your cycle and you can predict ovulation. If you have 30 day cycles (30-14= 16) you will ovulate approx day 16. Continue to use the ovulation sticks until you get a +. Or you could use the clearblue fertility monitor (link: http://bit.Ly/xwi55r ).
Delayed Ovulation . Delayed ovulation is common after a stimulated cycle. You can start testing now but remember that 20% of normal ovulations may not be picked up by home testing kits.