Hello,
I had the same situation that you have now. I would suggest to not listen about this amednment process because if you didn't land yet than it's not for you.
Amendment process is for those who recognize issues with their COPR while doing landing or after. But this is for issues not regarding entries dates but for example your name is wrong, place of birth is wrong etc.
On your COPR you have an instruction that if there is something wrong with your COPR than you need to send it back BUT.....
I have several issues on my COPR, my place of birth was wrong and first and last entry was wrong. So I did according to instruction and sent it back.
It took not more than 2 weeks to get COPR back.
What they did correct was my place of birth but not the entry dates. They explained that this dates can be only corrected during landing and it was.
During landing I just told the officer that the dates are wrong and he asked me for stamps from my first entry and last and when I showed it to him, he just put a notice on COPR, that's all.
So don't be scared of it, everything will be ok as long as you will just inform officer during landing about it.