There is a way to induce flowering early, I personally would wait but, if the plant is in your garden or close by, you can cover it with a black bag about 5pm and take it off when it gets dark, this will make the plant think the nights are longer, make sure you put 1 or 2 sticks in the soil to support the bag/s. When you first start it off, cover the plant longer, ideally you want about 24 to 36 hours darkness to trigger it off but you would suffocate the plant covering it for that long, it should have 12 hrs dark and 12 light for flowering.
Good luck +rep to all UK outdoor growers.