Our simulations shall provide you with an impression of the portfolio's performance under typical market conditions. To do so, we want the longest simulation range possible, but at least one complete market cycle, including growth, peak, decline, and trough. Unfortunately, many assets, primarily ETFs, have not been available that long, which creates some hurdles.
We settled for early 2007, which is right before the 2008 recession. This start date strikes a good balance between a long simulation range and limited use of proxies to substitute assets before their inception date.