It turns out the sims started automatically, on time, just as planned. I was under the assumption that Chiefs1 would simulate first, and when I checked it when I got home, no games had been simulated. But in fact, simulations stated in another league first. This is the first time we have simulated more than 2 or 3 leagues at once, so I wasn't accounting for how long so many leagues would take (up to an hour, maybe a little longer). As Cmcm2297 mentioned, you will get an email when the simulation for your league is completed.