I didn't write a timeline per-say but I called it "development of relationship". It ended up being 12 pages long and I wrote it from my point of view.
And I agree with jordana, you will not find a one thing fits all with your relationship. I tried finding the same before I wrote my own but I decided to let my heart flow and if that meant it was 100 pages then so be it but I will say that this part was the hardest part for me just because I am a procrastinator and knew I would never have as much time as I wanted to write our story the exact way I wanted.
I did give a month by month description of our relationship and I tried to describe things in full detail whenever possible. I wanted them to have a picture of it, as if they were reading a book. I wanted them to feel what I was feeling as those certain points in time.
I have omitted some things for privacy but here is a bit of part of our story. I hope it helps a bit. Just remember to type how things were and how you felt and don't TRY to make it to sound like something else. Make them feel your love.
"Sponsor and I first began communicating using the site that we originally met on in late May 2008. Over the next week we felt that we needed to move our conversations elsewhere since the layout of the site wasn’t all that intended for sending private messages back and forth. Sponsor later asked for my Yahoo screenname so that we could continue our conversations on Yahoo messenger and have a more immediate response instead of waiting hours for one message reply. After Sponsor asked, I gladly gave it to him. We both signed on to Yahoo messenger very soon after he received my message with my Yahoo screen name in it. As soon as Sponsor signed in, we began to instant message one another. In our discussions, we discussed our present life situations, what our favorite colors were, what our favorite foods were, etc. Some messages were more personal than others but most of it just depending on the moment. If we had a bad day or a good day, we discussed it together. Since Sponsor was finishing night school for English, we discussed how he was doing in that. It was also during these discussions that we discovered that we both were having a hard time finding our place in the world. We were both going through a rough time in life. Most of his was brought on by past relationships with people who didn’t appreciate him for who he was, what he did, and was often left feeling unwanted. I was having a rough time as I had just lost the most important person in my life at the time, my grandpa. It was nice and comforting in knowing that we both had someone to talk to and with someone that truly listened. Over time our conversations began to get deeper and have more meaning than just a chat with a casual friend."