You are correct. The soaks probably contributed to his difficulty shedding with the prior owners. Also, every snake is different. I have some that are in blue for several days and then shed, and a couple others that have a very short blue period and then shed in a day or so.

As this is your first shed, as long as you know there is adequate humidity, around 65 - 70% during sheds, he will likely be fine. A few questions - What are you using to measure humidity? What are you using for substrate? and finally what is your setup like?