Well for one, this is a post sharing how to make a google sheet work as a rebalancing tool not an educational piece on the topic of rebalancing. I did however mention in the first paragraph that a more aggressive rebalance strategy may be necessary in comparison to a quarterly schedule. The reason is quite simple, there is no one size fits all time period nor is there a set deviation from you target allocation that triggers a rebalance.

Regardless let me cover this question because it does come up. First of all when is a function of how often the vast majority of the time.

So how often? Thats up to you. But if you're totally unsure start with a 2 week period.

Now when? At the end of the two week period unless your deviation from your target allocation on all assets is less than 5%. If nothing as moved more than 5% wait for the next 2 week period.

Everyone will have a personal decision to make about these two questions because withdraw fees, exchange fees, network fees can impact a small portfolio more so than a large portfolio.