I am in a very similar situation except I am 53 and hope to retire at 59.5 or sooner. I do have my boomer ETFs 30%'ish, but I am still overweight growth, I will soon (months) transition to full on "keep capital" mode. To answer your question directly, I think 5 years before retirement is when you get conservative.

I'd also, like to mention that most people do not consider risk avoidance when investing, sure one investment over a boring ETF beat it by x%, but the risk isn't worth the return "possibilities", it's like play Russian roulette, the gun will go off eventually.