When to start building an e-mail list

Actually I have 2 questions. I am planning to do some tutorial series in a niche so this is my first question. Eventually I could have 10 tutorial series in this niche. I am thinking of a membership site. Not to expensive. between 10 and 20 a month. I am not sure if this would be better doing a membership site or just creating the series and promote it to my list and get some affiliates to promote it and just have a free website to go along with it.

So my next question, I want to build a list. I have the site but have no tutorials done. It will take a while to even get one tutorial done in just one series. I would get a list going but I don't really know how I would keep them interested and on the list. It could be a month or 2 before I get enough on the website before I would feel right about charging a member fee and it could be longer than that before I got the full product finished and ready to promote if I go that route. I am thinking in the meantime I could grow a list. I just don't want to feed them B.S. when they will be expecting tutorials.

I don't even have to say anything to anyone on the list I build about tutorials but that is what they would expect and that is what I am going to give them I just don't want them to drop because it is taking longer than they think.

I have some good ideas and plans for this and it will involve e mail marketing and I want to start the list now just don't know how to keep them around until the first product is done.

I guess I could come right out and tell them about the website or product in my first e-mail and then keep them updated on how far along things are and a little about what I am doing?

Any ideas will be greatly appreciated!
Thanks
Scott