what can i do more to introduce them in flower sta...

You should keep giving them your veg stage nutes routine until they finish their stretch. Then start to increase your bloom nutes to ensure they receive less nitrogen and more phosphorus and potassium which will help bud growth and density. You should also have/add some cal/mag on hand as during budding plants can deplete them quickly. In the mean time you can tuck or remove any large leaves blocking light to stems and bud sites. This is also a great time time to re position your branches to provide as much light & room for the buds. After she's done stretching you can remove tiny buds sites from the lower parts of the branches to direct more energy to create larger upper buds. Hope this helps