I like to use the Grahamanian "margin of safety" to illuminate my thoughts and feelings on this matter for myself. Generally, a wider margin is better, but each individual will have own level of comfort with what is wide enough. If the margin contracts after you pull chocks, you can always go back.
I achieved "FI" at ~35, pulled chocks at ~36, had 3 years of doing what I wanted, when I wanted, but a solid 2 years of that 3 was researching and developing my master's thesis project. Here are some of my thoughts on the experience of coming in and out and in (and out) of ERE:
* 2-5 years "feels" about the right duration for either a solid freedom period, or a capital accumulation period
* an academic objective, no matter how limited, can be seen as a "conventionally" acceptable explanation for a "career gap" in one's resume -- your resume may not matter to you (I don't really care about mine), but unfortunately it matters to other people with whom you may wish to enter a professional work relationship
* one downside to my first post-career freedom period was the lack of contact with collaborators on projects that interested me -- I was jamming on my thesis, which is by definition a solo gig, and my communication and collaboration skills most definitely atrophied -- I recommend finding collaborative projects with the "like-minded"
* I'm in my second Capital Accumulation period now, and managing to have a high level off fun with the project I'm on, though as always I find the upper/structural nature draining -- it's been about 1.5 yrs and I can feel the wear and tear beginning to show itself, thus I'm already looking to terminate this period and enter my second Freedom period (the Nullhof is an example of something I'm ruminating on)
* also wish to disclose that this Capital Accumulation phase has two purely economic sources:
- my margin of safety was high (in 2008 had investment income more than 2x my expenses) but has since contracted -- after my portfolio took some dividend cuts in 2009, my margin of safety was, well, marginally above my expenses -- I wanted to accumulate some capital to widen the margin, so I sought out temporary slavery
- my cash position was low (~10%) and with the stock (and briefly, bond) market retrenchment, I decided that my future periods of freedom could benefit from me accumulating a significant slug of capital and investing it while the market appeared to be in a down cycle -- so I sought out temporary slavery
- and one more non-economic reason for the temporary slavery: I'm temperamentally a contrarian and like to do things when others are not (gives me space and time to
breathe and think when there are no crowds around), so I figure if there is a time to suffer through the workforce, it's when the ranks are thin and there is lots of competition (i.e. rising unemployment) -- the challenge stokes me, and I feel much better working now than I did at the height of dot-boom when sign-spinners were being hired as software engineers -- I distinctly recall an uncomfortable level of excessive (employer) spending, inappropriate hiring sprees, and undue arrogance around technology ventures...the work was easy to find, salaries relatively high for the amount of effort required, and lots of eating and drinking, but the sense of life and struggle was not there, and I craved it
Too many rants from me recently. I will stand down and let others hold forth.
But one note: I have lost touch on this point...is 35-36 considered ERE "proper", by the given definition?