Since your growing outdoors, and it looks like the plants are in-ground, the plant will transition to flower once the day length decreases to around 15 hours or less. When this happens depends on where you live. Looking up Germany, August is when you should see the plants start to flower.
For the nutrients, what fertilizer are you using and when have you applied it so far? If its an organic fertilizer blend, general application is every 30-days. It takes time for the amendments to break down to a form that the plant can absorb.
For the pests, here’s an article I wrote on Spider Mites that will help you: https://mrgrowit.com/post/spider-mites-on-cannabis-plants/
I don’t have much info on snails but here’s a detailed article from another site: https://www.royalqueenseeds.com/us/blog-how-to-get-rid-of-slugs-and-snails-n422
