Do not feed any nutrients to the seed or even the first 7-10 days after they are above ground. The seed itself contains enough nutrition to make it for the first week or more of life.
Your soil likely has some amount of nutrients in it naturally also - depending on what soil you chose to use. You probably can make it the first month of growth without feeding any supplemental nutrients in most soils out there. There are however some soils that purposely have little nutrition so look into the type of soil you have and what it contains to decide when to start feeding.
I always go into solo cups for several reasons, but it makes sure you dont waste soil and space if you start in a bigger container and then it dies. Also, its easier to transplant and get the root mass out of a solo cup than most 1 gallon containers in my opinion.