I did a game a while back where my plan was to have 3 pregnancies with fertility treatment to see what would happen and if I could handle it all with 2 working parents. Two of them turned out to be twins, so I was raising 5 kids. It was quite hectic, but also a lot of fun. I did them as quickly together as the game would let me. In my save my eldest twins just turned YA and the youngest twins turned teen on the same day with the middle kid having 6 days left as a teen. The father is a 79 day elder, but the mother still has 2 days left as an adult. I don't remember why there is such a large age difference between the parents. I know both are CAS.
For careers, the father went firefighter and the mother went the cooking career (currently lvl
. She had lots of days off from all the kids, and the firefighter made for some flexible times, but I didn't use any sims store items and the only LTWs were fertility treatment, professional simolean booster, multi-tasker, and meditative sleep.
The only tip I can give is to have a job with flexible hours. My current game had one parent with a day shift and the other parent with a night shift (wasn't planned that way) which made raising the kids a lot easier.
For the most part, all I did was take care of their needs, find time to teach them skills, and leave the toddlers to crawl around and do what they want. As kids, all I focused on was meeting their needs, making sure they got to sleep on time, and making sure they did their homework. Everything else was left up to the sim (which wasn't much spare time after doing all that).