A plan is required. I've made many, although stuck to very few.
I read a book once. It said the start of your training plan should be to write down very carefully and honestly what your schedule is for the week. Then you can see how much of your already free time can be taken up with training.
Some things cannot be compromised: work; family time; meal times; travel; sleep. You see what you've got left, then try to fit in your training. Nice to drive past a pool on the way home but not so nice if you don't have time to use it, for example.
Also, remember a 30min swim takes 90mins if you're very speedy at changing and driving to/from pool. A 5km run eats an hour by the time you've changed into/out of running kit and showered etc.
You know all of this crap, you've done IM.
Meanwhile.... sportives with mates, parkrun as often as possible, occasional local TTs to see what it is all about, 10k races and aim for a local pool-based tri mid-summer. After that re-assess.*
Great to see you back JB!
*This is my plan. It might work for you too.