Viv size question

Hi so I'm getting my first snake soon and it's coming with a 10 gallon used viv, and I have a 20 gallon not-long sitting in my garage, I got it for free. Will that be too small for my snake to grow into? Also, when will the 10 gallon be too small?
Thanks!

I have read all over (forums, books) that a 20 gallon will suit a full grown corn!
My best guess is that when your corn cannot fully stretch out in her enclosure, it is time to upgrade. Many people on here have all kinds of tricks and rules for when to upgrade to a larger enclosure, I have seen.
I have a 15 month old corn in a 15 gallon, probably will upgrade in a few months.

I agree with the above but they do seem to need a 20gal long. I'm still a noob on here but corns like belly heat and they like to burrow into their substrate. I'm a believer that no viv is to big if there are enough hides so you can move to a bigger viv as soon as you want.

20 gall long vivs are the base minimum for full grown corns. Some may need a larger viv however if they're a large specimen. I believe if they can stretch out 3/4 of their body using 2 sides of the viv then the tank size is okay, don't quote me on that to be sure but I've heard that before on here I believe.

Sorry unrelated but nice to see another Calgarian here! Welcome. Are you getting your corn from Kijiji?

I found a breeder in airdrie via kijiji. I'm going next week to pick him/her up.

Yes I think I know who you mean. What morph are you going for?

Not sure yet, I don't know what the breeder will have. My favourite is reverse okeetee but I will probably go for a hypo or something close to regular.