Hey,
At 12 weeks my LO took around 5 naps a day and was awake for around 1 hour and 15 minutes in-between naps.
I didnt (and still dont) enforce a bedtime, I adjusted bedtime a little each day depending on when the last nap fell but I aimed for around 9pm every night and most nights he'd be asleep by 9.30pm latest.
Honestly I would say if you want to have a set bedtime you may need to start with waking baby up at the same time each day and trying to have naps at set times, but I would take into consideration that because babies change so much that you may find their bedtime changes/naps change etc and so having a set bedtime can be difficult. My DS is 6 months old now and he goes to bed anywhere between 7 and 8.30pm depending on what time he wakes up and when his last nap is.
If you haven't already I would recommend looking up wake windows etc to help with planning naps/bedtime etc. I use the app huckleberry and its helped me massively as you can track feeds and nappies etc too (comes in very handy if a Dr ever asks how often they feed or how many wet/dirty nappies they have etc).
In terms of tips to help naps and not fighting sleep, I can only say what worked for me as every baby is different. For us we have a particular routine we follow. So I give him a feed, then I pop him into his swaddle/sleep sack, pop his dummy on, then ensure the room is nice and dark, put his white noise machine on, and we have a cuddle. I pop him down in his cot just as he's dropping off but not fully asleep and he happily falls asleep himself. The whole process takes around 5 minutes if that.
It took a while to nail the routine I won't lie, I started with cuddling and rocking him until fully asleep then transferring, if he woke up I'd start again and just kept going until he was down and had slept for at least 30 minutes. Once I got it to a stage where I could put him down I just started shortening the length of time he was rocked for. We're now working on him not needing the rocking/cuddling but I'm not worried about how long it takes since the routine is so short anyways!
Bedtime the routine is exactly the same, feed, into swaddle, dummy in, dark room with white noise and rocked until drowsy then plopped down.
Good luck op! Hope this helps x