That is a loaded question/ topic.
Ideally you should know what you will do with all the babies. It might take you some time to understand and get the hang of keeping them. but it is not unlikely you will be over run in 2 months time.
I would say a 40-55 gallon tank would be good for all the babies. But as the babies grow you will really need more than one tank. This is because of the sizes as they grow they can eat newborns after they are separated.
Also if you have a female which has been at a fish store with different varieties of Guppies male and females in the same tank, they can take and store sperm from males for up to and even longer than 6 months. As in the female would likely be able to have babies for months without a male in the tank. All depending on the fish and conditions as my understanding
A 10G really isn't enough room. In 6 months with a trio, you could have the 2 Guppies and their babies birth, say 300-500 babies. Though it would not likely be they all live. Certainly not in a 10G.
You also would likely need to cull any deformed babies.
Not meaning to discourage you. Just be aware. If you have male and female Guppies, you'll have pregnant Guppies giving birth, whether you planned on it or not.
Hikari First Bites are a easy to come by tiny baby food.
