I've left pairs I thought would NEVER mate for days. Then 3 or 4 days later, I'd find them mating. Most of the time it's early in the morning, but not always. I've found a good match will mate within a few hours of being put in the honeymoon suite. Sometimes they get along well, but one or the other is maybe too old, or unsure of their gender assignment? I have males that just want to fight, or just don't get it, even after the female tried to teach them blowing bubbles. Then I have good mating and bubble nesters, that can't stay focused after a day or two with no sleep? Eggs are all over the floor on day 2, and they eat the eggs by day 3 or 4. I hate to tie up a tank to give them another chance. After 2 times, I donate them to the pet shop. I spent a lot of $ to get a hatch of my desired type of Betta fry before I learned the best breeders are less that a year old, and (in my opinion) suppliers most often send the "bred out" or bad breeders that are still good looking for an aquarium. Now that I have some I've bred, I need to wait for them to be about 6 months old and go from there. My advice is to buy only small, young fish and wait for them to mature. A big, good looking fish usually is a waste of $ for breeding. This is a great hobby if you have the time and patience. Best of luck to you!