It is a long slow drag - i think there will always be times when it hurts but we learn how to cope with those times rather than try to prevent them happening - to me acceptance is not as often portrayed as being something where we accept they are gone then suddenly miraculousely move on as if they never were here, but when we accept that we will always miss them and sometimes that missing will lead to great sadness, but also to recognise that at other times we will feel an echo of the things they said and did, things that were loving, kind funny, even mildly irratating - and with our parents the traits we recognise in ourselves as being from them.
But instead of them being always sad, as we see them as something that will never happen again, sometimes we will smile too ourselves and see them as part of our very rich past the people who made us and created who we are now, defined not by their loss, but by their life.