Hello, I'm new to this site and joined to find out more about B/W developers. However, I have, as I didn't have a practical darkroom until now, been playing around with cyanotypes for the last couple of years.
I highly recommend that you read Mike Ware's articles on this topic (MikeWare - Free Book Downloads). Personally, I have used Mike's "new cyanotype" formula which is much quicker than the traditional ones. I also use the sun (more shade than sun) and only require a maximum of 5 mins, usually 3, on a cloudy spring day.
I hope his site helps.
Chris