We are in First month of summer.why my girls are pre flowering?

Your plants "know" what they are doing. Better to start early and finish early, before Fall rains begin!

if your sun is setting at 720pm, it's clearly not a long day. this is biology of the plant and nothing else. It flowered because it got a long enough uninterrupted dark cycle. The required length for this flip to bloom varies by seed.

Depending on where you live in the northern hemisphere, flowering starts July 15-Aug15. But, I see you were at 18 hours of light in earlier weeks. So I assume you used a lamp part time to get to 18 hours. When you step down fast from 18 hours to 14, it will trigger flowering. I see this happening in week 11 on your grow. The light green new growth is a sign. How it goes from here can vary. Some indica can settle into flowering and keep going- this is your best outcome. Sativa stems to reflower and you will get foxtailing on your buds and end in October. In either case, going from inside to outside has to be timed exactly with 3 minute reductions per day. It’s a pain. Check out my light deprivation grow- you can do this and get great plants. Best of luck with your grow.

Depending on your geographical area. summer hours are close to 12/12 at the equator. but where I'm from its closer to 18/6 So you want to measure out how long they are getting darkness for. some strains need aorund 10hrs darkness others a bit more. also if it is heavily shaded from other buildings and stuff it might increase that darkness period before light hits em. Will it bounce back into veg mode, maybe if the light is greater then 12-14hrs a day. you will notice this new regrowth is odd and lots of single finger leaves growing out of the bud sites. But I don't think this is going to happen. It does indeed look to be in flower, I doubt this is it just showing sex, its a bit aggressive. Maybe the shop that sold it to you misspoke when they said it was an autoflower, and that it was an autoflower mix? I have heard of fast versions "photoperiod + auto" not being great mother plants and turning auto in the next vs photo. There is not a lot we don't know about them as they are someone what new on the market. Maybe after a long veg time the auto part takes over? If the other photoperiods plants are ok its a working theory but not proven. I agree with other answers in previous questions to have an auto veg out for 15weeks is unheard of. not to say its impossible but it would not be something someone would want and it had a lot of stresses like topping so it seems highly unlikely. Just keep giving it lots of love and maybe more food given its entering flower and will be eating it up. Your plants are looking good so well done.