Give them some flowering nutes, it will help them have the extra Phosphorus they will need to start forming flowers. If your worried about your plants getting to big during flower theres alot of ways to minimize strech some easy ways are to add cfl or mh 5500-6500k spectrum light to the plants during flower(along with the normal 2200-2700k hps lighting). Dont use ferts high in nitrogen during flower because it will cause more vegative growth and will can cause the plants to strech. There are also chemicals that can minimize stretch. You could also lst,scrog,ect if your worried about height. Cannabis can double or triple in height during flower depending on the strain , and the methods you use to minimize it. If you want thicker branches get a rotating fan on you plants those things help alot. Also alot of people dont mention this but root mass has ALOT to do with bud formation the better the root system the bigger the plant will be able to yield. Use as big of pots as you can, its something thats overlooked alot of times. You can check out my current grow the link's at the bottom of this post ive got some recent close up pictures at how my buds are forming at day 8 of 12/12. It will give you something to judge you buds formation progress at since your plants are only a few days younger in flower then mine. Stop by my thread and tell me what you think lol.