First off, I agree, there are no rules to follow. Back when I started rotation play in Sims 2, I would play for three Sim days, ending the third day at midnight. Switch to the next household and play them for three days, and so on and so forth. I made a chart for myself using those little squares underneath each day of the week. I would fill in the square with a marker (highlighter) to show me where I was. I used the same color for all households for the first 'round. (This was very helpful, should I have to quit for the day before I'd made a full 'round. Also, this ended the argument with myself as to which household to play that day, because I knew at a glance where I had left off.) Then switch colors for the next 'round. I did this up front because I wanted my Sims to age evenly. In Sims4, I have aging on for Active Household only, but I also play for a full seven days. That way if I want a Sim to have a baby, I will be there when it comes and the game won't give my precious new one a name I can't tolerate! (Yeah, it's happened to me in the past. Sticky thing is, you can change it in CAS, but you can't bring baby into CAS until they reach toddler.) I also use mods, MCCC being the most important one to me. I just made a delightful discovery with it, too. (Late to the party as I often am.) You can pause a pregnancy and then unpause it later on. (I had a couple of random woohoos, due to another mod I use and there was a baby on the way I wasn't yet prepared for. How dare my Sims go off script!)
Best advice I can give is play around with it, see what works for you and what helps you enjoy the game. Nothing worse than playing and not enjoying the time being spent. Hope this helps. :)
