You can get one now. Or of they are really tiny, maybe two but 10 gallons will be only a temporary home for them. I think it will be o.k for about 4 months, that's about how long Sebastian Pearl lasted in the ten. As they get larger you can really see that they need more room.

The only thing I would use a ten gallon for is a hospital/isolation tank or as a peaceful community tank for very small fish (And not very many of them.) Put some live plants in there, too. Anubias are usually not eaten by the goldies but they will provide better water quality for them.
I think it is really important either to 1, to get all the herd at the same time (in a large basic tank) or 2 to go slow and get them one at a time, and allow the filter bacteria to catch up and allow you time to observe and treat them in a hospital tank for health problems.

I have a brand new goldie (a butterfly) in our hospital tank right now. So far he's doing fine, he has 6 tsp salt in his tank and just a few rocks and gravel to hide around.  His name is Cocoa Pearl and he's a bronze, looks a lot like a Moor but has less pronounced eyes and a lovely tail. He's about two inches long.

How quickly are you going to upgrade? Will you be able to do it before they have health problems from being over crowded?

They would be stunted at the very least, of course you would have to watch amonia like a hawk. You would end up with very frequent water changes as they get bigger like every other day...I was doing 50% water changes very frequently towards the end of Sebastian's stay in the ten gallon. There is no wiggle room in a ten gallon tank. No margin for error or laziness about the water changing, I mean.
Do you know what size tank you will need to upgrade to? How many goldies are you planning for?

Yeah Id say for three and a snail 20 gallons would be minimum just for a couple months at first if they are very tiny. But you really only need a 30 gallon for 3 goldfish and a snail.

Yes they are perfect together.

Yeah they get fish lice and other diseases in their heads.

I'd agree with Nossie, it would just be better to wait a few months for the bigger tank and in the meantime do a little research

The other risk with putting fish in such a small tank as a 10 gallon, is that the water quality will be un-stable and will not be very good quality. The fish will effectively be living in their own waste, which can make them sick or even worse, they can die from it.
Trust me, I had 2 goldfish in a 5 gallon tank and I lost Star within a week. I would hate for you to make the same mistake.

If I could have, I would have gone for a larger tank to begin with, rather than going smaller and losing one of them.