When do I change over to flower

Switching into flower before your plant has shown it's sex isn't a good idea. It can push the plant to hermaphrodize, believe it or not. Let the plant show you if it is a male or female. Then, once it does, you will be able to flip it into flower. I suggest trimming off the big shade leaves that cover bud nodes and letting it fill out for another week or two. You'll get a much better final weight and product.

You can switch to the flowering stage as soon as the plant has established a solid root system. In optimal conditions, plants should be kept in their vegetative stage for approximately 60 days. This time period should give the plant the opportunity to maximize yield and acclimatize to growing conditions. Hopefully, this was helpful and if you need more help feel free to shoot a message I'm glad to help any time.