Some people have time to plan and get ready and some are just thrown into it by circumstances. For me I had a lot of time to plan and think about it. It took a while to downsize and do my build. I got my van just under two years ago and just went full time the beginning of this month. So for me it was a long time to plan and get ready. But I'm glad I had the time. Now that my van is mostly done I feel pretty comfortable in it. But I imagine it will be different for everyone.
If you have the time to get ready it is a luxury. I think the more time you can take to prepare the easier it will be when you make the leap. It was for me. The last two years also gave me lots of chances to do some urban and regular camping. I've taken plenty of short and long term trips so making the move to full time was a lot easier.