My 1 month old son has one eye bigger than the other. Is he suffering from ptosis and can it be fixed in the future?

My baby have exactly one month and 5 days, as you can see in the attach photos, he can’t open one of his eyes completely, I went to the doctors and they suggest us to wait until his grow, for example till 15years or more, and after that he will need the drooping eyelids surgery, right now they gave me the eye drop , it was effective also, we are really confused and upset because of him, please tell us is it better to do a surgery now or waiting as his doctor said ? Thank you in advance