Exercise

The best time to work out is the one which works best for YOU. If you're a morning person naturally, exercising in the morning will be easier for you than somebody who's a night owl. If your mornings are a rush to get done before work, maybe afternoons or evenings allow for more relaxed time to yourself.

If you truly do not care, some studies suggest the body has a very slight benefit to exercising in the morning, but the difference is so small that you can work anytime of the day to good results. The only exception may be avoiding exercise immediately before bed as it can make it hard to fall asleep, but some people can get away with even that.

How often to exercise is a little more defined, with multiple agencies suggesting 150 minutes of moderate exercise (think working up a light sweat, heart beating a little faster, maybe breathing a little harder) or 75 minutes of vigorous exercise (working hard) per week, spread however you want: 10 minutes here, 60 minutes there, etc.

Your muscles get more benefit from being used twice per week instead of just once, so at least two workouts per week is good. On the flip side, your body will rebel and NOT get better unless you also add in rest days, at least two per week. So choose between 2-5 workouts per week is a good starting point, with beginners starting at the low end (2/wk) and gradually adding additional days as you get used to moving and working.

So let's sum up:

2-3 workouts per week to start with the total gym, maybe 2-3 workouts per week of cardio (walks, jogs, swim, sports, etc), at least 2 days per week doing nothing more strenuous than household chores

Keep your lifting sessions under an hour each to start, cardio can be longer if moderate intensity

To add to nossmf's excellent advice:

Depending on where you're starting from, even that much exercise could be a lot. If so, work your way up to it gradually. Over-fatigue is not only discouraging, it's not great for the body (physically stressful, among other issues).

Strive for a manageable challenge from the overall workload, something where you have to try hard during the session(s) but stopping short of true struggle; where you maybe feel "whew" for a few minutes after the exercise session(s) but feel energized for the rest of the day rather than dragging through it from fatigue. You might get some muscle soreness at first, but after an initial short time period of adaptation to new exercise, there should not be extreme soreness or stiffness that interferes with your day . . . maybe kind of a pleasant worked-out tautness feeling, once you get into it.

If you start realistically from where you are with a manageable challenge, before long that routine will become un-challenging, even easy. That's fitness developing. As that happens, increase the duration, frequency, intensity or change type of exercise to keep that manageable challenge in the picture. Manageable challenge is the sweet spot, IMO.

Even if starting from a point of being deconditioned or needing rehab, you can gradually work your way up to the recommended levels of exercise over a reasonable time period.

Best wishes!

Echoing other advice -- what works for you, and when you're most likely to stick to it is the main thing!
For me, that means a morning workout. While I'm not a morning person, I find that after a long day at work, needing to get stuff done around the house, afternoon house chores like mowing or whatever, and then cooking dinner, etc, if I don't workout in the am, I am inconsistent at best, and very likely to just never get my workouts in. I can't do it right before bed, or I can't sleep.
So AM before work is best. If I do that, I am more consistent, and it's done regardless of how much craziness the rest of my day throws at me. Plus, after all day, I can get home and do my stuff without worrying about trying to also get a workout in. If a project takes longer than planned, not a problem.
My workouts this week will be pretty light due to a (mostly minor) injury this past weekend, definitely ease back into it and be cautious of pushing too hard, too fast! Give your body time to build back up and work through "stuff."