Thanks for your advice, i just watered my plants.
should i transfer them to a 16oz plastic solo cup now?
This is just my 2c.
Many ways to succeed.
Should you transplant? Yes.
Should it be to a solo cup? IDK
It's hard for me to guess what is the best choice for you.
Some growers might do well to put them in 16 oz cups and then transplant again in 10 to 14 days to a 1 gallon pot.
Others might do better transplanting to a 1 gallon pot and bypassing the solo cup at this stage.
Then you would need to transplant again from the 1 gallon pot to a permanent pot, could be 3 gallon or 5 gallons, some may go larger.
It can be done many ways. I've started seeds in 3 gallon and 5 gallon pots with no transplanting involved with no problems.
Transplanting itself takes experience and if not done properly can stress the plant.
If you are familiar with auto flowering plants people that grow them usually start and finish in a 3 gallon pot.