Lost Soul is on the money as usual
Cycle Insurance run at full dose will last for 30 days. If you run a 3 week (21) SD cycle I would start the Cycle Insurance 3 days prior to the start and run whats left into your PCT.
3AD has been reformulated since I last looked at it, but I believe the central ingrediant is still Adrenosterone? which if ran at a high dose (> 200mg) would still warant PCT.
Is this your first cycle?