Need repotting advice

Hello,
I recently grew a red maple from seed after cold stratification. The seedling is now about 4 inches tall, and i am not sure what to do next! Do i need to repot? What are its watering needs?
If anyone could help with basic techniques this would be great.
Its currently in a little cardboard pot with bonsai soil, and looks like these, but the head has already gone, and it is a little smaller.

I generally let seedlings grow for a year before repotting. I think this is particularly good advice for those who are new to growing seedlings. Once you have some experience, there are some tricks and techniques to get more uniform roots that can be applied to young seedlings, but if not applied correctly you end up with dead seedlings.

Thank you, a year seems a good amount of time