any ideas for what's the ideal level of "maturity" for transitioning in-house? The in-house salaries are quite lower than the firm salaries, so I might milk the firm life for a bit more. Are you better off transitioning in-house as a mid-level associate, as a senior associate, or as a partner, or does it even matter? I know pirates value combat experience, but there is something to be said for hiring young strong soldiers over experienced but crippled veterans.
Speaking from limited experience (I have been in 2 in-house patent depts and know how a couple of others are organized and hire), I'd say there's no maximum (with a qualification to come) but definitely a minimum. You'd seldom get hired in-house without 6-8 years practical experience (some of the years could be PTO experience). Exceptions here include political fights between HR, Finance and Legal where the position gets authorized for an 8-10 year lawyer but you only get enough money to hire at 1-2 years experience (even considering in-house salaries are bound to be less than at good sized firms), so you hire the near-noob and hope for the best.
Relatively young partner level folks (10-20 years) might be a fit for a team leader type position in-house. In a company with a large patent department this is a position where you lead a team of 3-8 others, carry maybe a 1/4 docket yourself, and act as the main patent advisor for a business unit. Nice slot for those who are getting burned out by P&P. But most often I've seen these filled from within or by scalping from other companies because there is the considerable question of whether the new hire will be able to fit well and work well within a corporate setting. I have not seen a case where we set out specifically to hire a 15 year man for a worker bee type P&P role, although these folks do sometimes fall into your lap.
The only times I've seen very experienced people jump in-house was to take over a dept chief role.
So after reviewing the above, I guess I come out with "don't wait too long" (more than about 10-12 years experience, and you might be better at 5-8) if you want to go in-house.
FWIW going to some of the other recent comments: I talk to people fairly regularly in a number of other corporate law depts and they are cutting staff and lawyers, failing to fill for attrition, etc., and being told to just make do. I work about 60 hpw routinely with spikes depending on what's going on litigation-wise. One of the drivers causing me to leave my last in-house position was 70+ hour weeks due to a "temporary" situation that after about 15 months looked like it was not going to end. So for anyone thinking about jumping in-house, if you interface with client in-house patent attorneys why not have some frank discussions to get an idea of what they really work?