Start with a 5 or 5.5 gallon glass tank if you can. Zilla has Critter Cages at 5.5 gallon, and Pet Supplies Plus carries them and they are usually on sale for like $10-15. Sliding lockable doors, light weight and easy to clean. 10 gallon can work, but for some baby bp that may be too big for them. Concern with glass tanks is keeping humidity up. You can look that up about how to maintain humidity in glass tanks.
Personally, 6 qt tubs for baby snakes are awesome. They are too scared and don't want to be seen (yet) anyway. At the start, it is more about what works for the snake and then later you can make comprises and make it what works both you and the snake.