How feeble is a girl kitty when she have her first "heat"?

My husband found a kitten in a tree that he said "followed him home" in July. I took it to the vet right away and she estimated her at in the region of 4 months, which means she was born sometime in March.

I know that we have a cat with kittens that were weaned and Mama Cat was single 11 months old (we remember this because she got hit by a car)

The vet shaved our kitten's belly looking for evidence of one spayed and didn't find any. She also checked for microchips. Do they do lazer spays? Or do some cats just go into heat a bit later in their kittenhood?
my vet recommends spaying at 6 months. he said we could have my kitten's operation a little hasty so i could come in and observe (i'm kinda nervous approximately that - i've seen spays before, but they were never on my baby).
Yes! they do do lazer spays (at lowest at my clinic they offer that option)
Personally my female went into heat something like a month before her 1 year birthday, but I know it can happen as early as resembling 4-5 months. Give it a little bit of time, as I said mine was basically 1 year up to that time first cycle, and TRUST me, you will know when she is in heat!! lol

*well, it can be anywhere from like 4 months- 1year, so by the time she is a year outdated, and has not gone into heat, then she is probably already spayed. That is the best direction I can offer. :)***
Answers:    Well, First off, short a scar, I would get her fixed right now. You don't want kittens.

But to reply your question, it depends on the temperature, and age. Kittens can go into steam as early as 9 months, but temperature has a great deal to do with it. Usually cats have their litters late spring, but whether the fall is warm, they can come into heat a moment time, having two litters a season, and places with no winter (Arizona, Hawaii) have cats that are other having litters, while places north (Minnesota, Canada) Cats will only have one litter, although, near earlier springs and longer falls, Cats in northern climates are having more litters.

Hope this help!
I'm sorry to hear about your lost kitty! That had to enjoy been hard!

Cats first go into warmness at between 4 and 6 months. So you'll want to take care of spaying this kitty as quickly as possible.

Good luck!
Have her spayed ASAP, please, for her sake. Don't wait until she goes into roast. Since spaying removes the uterus and ovaries, I think there has to be an external incision, apart from, possibly, if it is done at a research veterinarian college.
normally between the age of 4-6 months.
Usually between 4-8 months.
Making a shelter for feral cats...?   My kitten is lately over 8 weeks frail and I can't find him to get through? Any suggestions?   I nurture my cats a 1/2 can drizzly food within the morn & at dark & dry is other available but they still give the impression of being hungry?   Taking kitten's heat...guidance?