Here is what I am getting in regard to your relationship. Remove your desperation and focus on doing things for him that are completely selfless, that you have nothing to benefit from. It will not be something degrading to you or that others will see and commend you on.–just something supportive that will make his life easier and show you truly care about him not about you getting him to commit to you.
Expression of love is not a goal or worded contract. It is an everyday dance of giving, trust and respect. Bring the two of you closer by giving without motive and he will either say it to you or you will say it comfortably knowing you will get the response you are looking for. As far as when, it’s hard to say. Some ice has to be broken first, though I will guess 2-4 weeks.