Q.When Do You Transplant the Little Tomato Plants to Bigger Pots?
I am very, very new to gardening. I’m growing some veggies from seeds. Roots look good, plants are small but are growing, and they all have their first leaves. When should I transplant them into something bigger? They are tomato plants. I started them in small plastic cups with holes in the bottom. Also, none of my hot pepper seeds grew. . . any suggestions? I kept all my seeds moist and in the dark until they germinated, but nothing came of the hot peppers, so I moved them to the light. . . still nothing. It’s been 2 weeks.

Certified GKH Gardening Expert
This article will help with moving your seedlings and applies to bigger pots as well as garden: https://www.gardeningknowhow.com/garden-how-to/seeds/when-to-transplant-a-seedling-plant-into-the-garden.htm
As for the pepper plants, they require warm temps to germinate and grow so they may simply be slow to start. Give them a little more time.