Pots and soil

What would be a decent final pot for a plant? I bought a 3 gallon pot and wondering if will be an issue for the development of the plant. What size do you use?
Also, any problems if i would plant the sprout in the final pot from the start? I would like to skip the transplant part as i know that it can delay the growing process but also because i don't know any reasons why i shouldn't.
Regarding the soil... can't seem to find substrate that don't contain nutrients. I was told that time-releasing nutrients soil is not recommended for the first phase when growing a plant before transplanting. But because i want to put it in the final pot from the beginning, i wonder what soil should i use? I can't find happy frog around here or something similar, but found BioBizz Light Mix which states it contain low to moderate nutrients. I can also use CANNA TERRA PROFESSIONAL but i don't know which would be the best between BioBizz and Canna Terra.

Any advices regarding all written above?

Coco doesn't contain nutrients.....it's inert.
You can grow a tree in a 3 gallon pot with coco.
I start in solo cups for the first 2 weeks then transplant to 2 gallon pots........it's easier to maintain the proper moisture level.
Done properly, there shouldn't be any slow down in growth due to transplanting.........mine never skip a beat.
Good luck.

Canna terra is more of an inert substance like soil. If you're using canna terra I end in a 20 litre fabric pot. Could probably go a bit smaller. I use chemical nutrients from Dutch pro . Make sure to let the medium dry out between feeds. If using Coco you can have a smaller pot but must keep an eye on the moisture levels. I put germinated seeds straight into canna Terra pro give it a good watering a few days before ready to pot then just mist until the medium is dry. It helps the roots grow deep in search for water