Stray

Planning on having our new stray cat fixed but can't have it done for a month we have her confined in our closed in front porch. She doesn't seem very happy since we let her out this past Sunday. What I want to know is we want to let her out but need to know how often a female will go into heat so we know to get her in before that, anyway of knowing like how frequently or something.

Every 9 to 13 days according to this link so get her spayed asap.

Cats don't need to be in heat to get pregnant, they are induced ovulators so if a tom gets to her at any time she can wind up pregnant.