I really dont like to advise on nutrient additions, other than SuperThrive with every water. Too many people fuck their shit up because they think the plants need nutes that arent in the dirt....and they havent done a dirt analysis.

The only nute I give during veg is the bat guano..... helps them grow.....

Then in flower i use a flower nute....

Just be safe and use 1/4 what they want you to. Tomatos dont need a whole lot of nutes in a good soil or dirt base. I use 1/4 strength 1X week.

No I dont think you want the fish mix at this time. Flowering time it sounds suitable...not veg time.

Good luck