I am not sure that you are accurate on that. I have never run into that myself and I don't recall any such restriction when I took my graduate class in S-Corps, nor anything from continuing education. Do you remember where you found that? I did a brief search and only found that an entity could revoke it's S-Corp election, with nothing about any time restrictions.I think it is important to consider not only federal taxes but state taxes as well so it is good that you have reached out to a tax attorney in Oregon.
To add a caveat to what Taxing Matters wrote: You cannot just switch from a C-Corp to an S-Corp and back again at any time. You must remain an S-Corp for at least 5 years (I believe) before you can make a change.