7 years just like Jacob in the bible Lol just kidding though.But seriously what kind of work are you referring to,because I know love is about two people and everyone involved should work at it. Why work alone and wait for a yes,this is more of a Boss and employee kind of relationship and not love. I always say that love is like a partnership where all partners involved work at it from the very beginning to have a solid foundation. The two involved will always discuss their plans,aspirations, visions, dreams and all of that together before any proposal. Don't be shocked when you propose she says No, because it might be you were the only person in the relationship and she wasn't part of all the plans.So to get the sweet Yes you should first strike a balance, define the relationship and leave everything open for deliberation.Duration should be how ready you are so take your time to get it right first.