I like to see at least 3 or 4 good hookups over 3-4 months before I feel reasonably confident. That said, last season I obtained a good size female very late in the season-threw her in with my best male pastel on June 5, but within a day decided it was too late. I decided i'd concentrate on conditioning her for the fall season. They hooked up once.
You guessed it- from that single copulation she dropped 5 good eggs on October 11th, producing 1 normal and 4 beautiful pastels November 27! So sometimes, one is enough.