I usually hold the female outside the male's cage and watch the reactions. This way they can't hurt each other while you figure out whether to put them together or not. If the female rocks back and forth, turns dark, gapes, hisses, lunges at the male, etc. then put her back in her own cage...she's not receptive or is producing eggs already. If the male behaves in an aggressive manner put her back in her cage. If the male is not in aggressive mode and the female is calm, doesn't puff up or hiss or rock and may slowly walk away from the male then she is likely receptive....and the two can be put together....but contingent watch them in case things go wrong. They can be left together until the female starts rejecting the male by hissing, turning dark, rocking, gaping, etc.