When do you start playing a new sim?

I bounce around all over the place. Sometimes I'll take an NPC and raise them up to the highest career level or take them on a Granite Falls/Selvadorada vacation or I'll take the kids of my prior-generation sims and follow their adult lives. Other times, sims I've played briefly in stories that went nowhere get brought out to feature in some story I'm telling on the forum (I've done two "musical theater" bits, setting a bunch of screenshots to song lyrics, and have plans to do more. The hard part's finding classic songs that have words that fit well with the game's theming.) I've even nicknamed such sims the "Background Players".

My simworld's coming up on its 2-year anniversary (Feb. 20) on this computer. One save and over a thousand hours.