Nutes help

Okay so last time i added nutes and they were WAY too high but long story short im restarting. but I just bought nutes when i went to the store and i wasnt planning on buying for my plant. I bought miracle-gro 8-7-6. Its liquid and is for houseplants. What would be the best time to add these to my plant. i just did a complete upgrade on everything i had, i got a bigger growing container, and newer soil.

....was your plant potbound when you transplanted it? ( age of plant?) ..what size pot was you in? ....what size pot did you transplant into?
Typically, soil comes enriched enough to last a month or so...however, if your transplanting say a month old plant from a 1 gallon pot into a 2 gallon pot...it may need fertilizers within a couple weeks because the root system would be well established. Many of factors....

Oh sorry i should have mentioned it.. im completely starting from strach with my new plant. I belive i killed my plant before it even sprouted, its a long story but i did nothing wrong at first and it didnt sprout for a week. I did germinate it but it took 4-5 days to germinate so maybe it was just slow. But whatever that ones gone and i just started germinating a new seed right before i started typing this. I realized i wasnt as prepared as i thought i was so much my equipment got upgraded, got new soil and nutes..