tl;dr: What are your mechanics for altering your asset allocation? Do you do it over time or in one swift action? How do you avoid using this as an outlet for speculation?
mid length read:
I currently have an allocation of 80% VTSAX and 20% cash.
I've recently warmed up to the idea of moving to a larger house, perhaps at some point in the next 6 years. If housing happens to go "on sale" I could see making a purchase in about 2-3 years. I would keep my existing house and turn it into a rental property.
Such being the case, I see value in having more cash on hand than I currently do. I'd hate to pull money out of VTSAX when it's potentially on a low (imagine a bad stock and housing market at the same time). I would need a decent chunk of cash by my standards as I do not like to carry a mortgage, or much of one. My current property is paid off.
This being said, what is the best approach for changing an allocation percentage, such as to one of 70% to 30%? Is it done over time? Should I force myself to only do it at a specific point in the year, thus minimizing how much this masquerades as an allocation change but is actually my monkey brain finding a way to speculate about the market?
Another tidbit worth knowing: I receive a large distribution from my company quarterly. Currently, it's about 10% of my net worth each time. This could also be used to change the balance.