Colliding your opening buys on turn 5 is extremely bad no matter what they are.
Edge case: Curse/Curse.
You're not doing it right. If oyu collide your opening buys Curse/Curse T5, your opening buys were Curse/Curse, and that's also extremely bad for you.
The real edge case of course is:
Board with Baker and Doctor. T1, use coin token, buy Doctor, overpay with 3, thrash 3 Estates. T2, have 5 Coppers, buy Bandit Camp. T3, have 2 Coppers, Doctor, (reshuffle) Bandit Camp, Copper. Play Bandit Camp, draw Copper, play Doctor, trash 3 Coppers, buy Masquerade. T4, draw Copper, (reshuffle) Spoils, Bandit Camp, 2 Coppers. Play Bandit Camp, draw Doctor, play Doctor, trash 1 Copper, buy Goons. T5, collide Bandit Camp/Doctor with Masquerade, Spoils, Goons. Play Bandit Camp, draw Copper, play Goons, play Masquerade, draw Copper, Copper, pass Doctor. Buy King's Court. That wasn't so bad, was it?