I dont think the gap matters that much tbh, although I did my 3 levels consecutively. But I didnt remember jack shit after 6 months of break after passing each level. So every level was a new level to me, with minium amount of knowledge retention from previous level. I’d be more worried about your commitment issues, after all you havent done any studies since 2015, it’s hard to be in that studying mode again.
I totally agree with Asianrepresents. I really don’t believe that passing a level depends 'that much" on how good I was at the previous level, whether I remember it all or not. If you study the materials at this particular level, you will pick it up. But like they said, committing after a long break is difficult, this is the real challenge.
I took level I in 2009, and then didn’t get around to taking level II until 2017. Failed that one, but stuck with it and was able to pass it in 2018, and Level III this past summer. Took a lot of effort and sacrifice, but it can certainly be done. As for order, I did the same as referenced above, although i think the books are potentially numbered somewhat differently if I’ve read correctly. Best of luck.
Have you already registered for L3? I want to know if there is any expire time frame to take a certain level. I heard years ago that if you don´t pass the next level within 4 years, you will need to repeat the previous level exam.