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The best guess as to when they'll give birth is likely sometime in the next 2 - 3 wks. Unless you know the last ...
The best guess as to when they'll give birth is likely sometime in the next 2 - 3 wks. Unless you know the last time they gave birth, to predict it any closer than that would be impossible.
Please don't try to "speed up" the process. All you will end up with is premature fry, which can lead to many health issues. There are some thing such as this where nature just has to take its course and all we can do is wait.
Your breeding tank looks a bit bare... I wouldn't expect much to survive in there unless you can catch the females as soon as they give birth.
You might want to try adding something such as hornwort, java moss, or naja grass. Dense plants where the female can't reach the fry is the easiest way to ensure the fry are not eaten by the female. If she can get to them the female will eat as many as she can (or all) of the fry pretty quick.