I'm going to take some time here to be detailed so I can copy and paste parts or all of this in the future. Sorry for being long winded.
Many on RIU use epsoma garden tone 3-4-4 or tomato tone 3-4-6 with great success.
Different strains have different demands. My long flowering strains have higher nitrogen demands so I always prefer something higher in nitrogen. Indica plants tend to have less demands for nitrogen.
For balanced ferts I prefer.
Happy Frog 6-4-4.
DTE Bio Live 5-4-2.
FF marine cuisine 7-7-2.
If you want to get into all of the different types of single ingredients check Out the DTE website.
Lots of good info on this web site
https://downtoearthfertilizer.com/
Two of my favorite dry amendments are fresh earth worm castings and kelp meal.
If not fresh EWC a bag can be purchased it just won't be the same quality.
There are many ways to go, if it was me in 3 to 5 gallon pots. I would probably top dress with 3 TBL of the DTE bio Live. I'd also add 4 TBL of EWC and TBL of kelp meal
That would leave me at water only with the occasional addition in the water of either a low dose of epsom salt 50-75 ppms on the 500 scale. Occasionally seaweed extract 50-75 ppms. The next one is not for everyone lol. Fish emulsion 5-1-1 on ocassion to feed the microbes when a N boost seems needed. Mix it outside and I use about 100 ppms maybe 150. My doses are low.
When to top dress again depends on the soil and the plant. Might be best to top dress again in 3 weeks. Might be better to wait a week or two longer IDK.
That's where EWC and kelp meal come in. When not sure what to do next they are both very safe amendments to add and will help maintain a plants health while figuring out what to do next.
Organic growing is not for everyone. Many will prefer to grow with synthetic nutes in coco or other hydro methods for good reasons.
A well liked book for getting into organic growing is teaming with microbes.