Hey, it might be best for someone else to answer this question... But I think its roughly about 28 days after getting pregnant, so maybe put it in about 25 days after you noticed the gravid spot, this also depends on the size space she is going in. If its a breeding trap don't put her in too soon as this environment is stressful for them, if its a small tank with some swimming room put her in whenever you like really. Hope this helps, i don't know the time for certain and haven't really bred swords... :oops: :-? (Thought I would type an answer incase noone else does though )