You need to know how are flowering the females for this.But to know how many time the female have before engaging senescence. Needless to say that it almost change with each strain.
In doubt the “ping pong balls” stage is generally safe, the stage of your beautiful plants minus a good week.
It’s good to show how things can go wrong too, this one stayed over a month dusted by the fresh pollen of the male aside. Without much success. This specific pairing is complicated to make, it’s rare but problems of compatibility exist between the tubes of the pollen and the pistils/ovula system of the females. On this pairing it’s like crossing an elephant with a guinea pig ^^