how much time untill harvest, will the buds grow bigger and how many dry yield.

Heya! If you judge by the pistils usually 70-90% ambered is a good time to harvest. The best way is to use a small microscope or jewelers loupe to have a glance at the trichromes. Most people harvest when all the trichromes are milky to 30% amber. If you harvest with more milky trichs it will produce more of a head high effect, where as more amber trichromes will give you the couch lock effect. I would suggest looking at the trichs if you can, I have had plants ready to harvest with lots of white pistils left still and some where they were all brown. Cheers and good luck!