Nutrients during Pre flower and when to switch?

https://www.biobizz.com/wp-content/uploads/2023/10/EN-Nutrient-Schedule-EN-2023.pdf

BioBizz suggests in the feeding chart, that you use Bio Grow instead of Fish mix, when transitioning into flower. By the Looks of your plants, you can start using Bio Grow now, the additional sugars should enhance the taste of the final product

After the stretch. but you can still use fishmix to the end if you want. just don't foliar feed with it. https://www.biobizz.com/wp-content/uploads/2020/03/Nutrient-Schedule-EN-2020.pdf

Do not switch until there are small "budlets" formed......pre-flower is not flowering and cannabis still needs adequate nitrogen in early flower to help with the "stretch". In other words, not until 2-3 weeks after the first pre-flowers appear.

If your product doesn't give a formula for the transition phase(mine does), I would recommend continuing your veg schedule through the transition until you're at about 2 weeks into flower. Early flower involves a lot of stretch typically and you'll find that those who switch too early run into nitrogen deficiency usually.

You can refer to the feed chart below. It shows that you feed Bio Fish all the way through flower. You also start adding the others along side it the first week of flower. Some nutrients have you using everything all the way through but in different quantities. Appears Biobizz is one that has you using all of them through bloom. Hope this helps.

Do so when you see flowers start forming, during the preflower stage. Good luck!