Re: WFHSS
I once worked from home for a straight 17 months and in that time, went into the office fewer than 6 times.
After spending the previous few years living a nomadic lifestyle it was, initially, blissful.
But I did eventually start to miss the social side of work - the actual face-to-face interactions with colleagues.
Since then I've tended to work a day or two at home here and there.
I did learn some valuable lessons:
If you can have a completely separate working space, do so. I was fortunate enough to have had an office built in the garden and it was both a lovely place to work (especially over the summer) but also meant that at the end of the working day, I physically closed work off. It makes a surprising mental difference.
Stick to your contracted hours. Obviously, there will be the odd time where things happen that push that out of the window, but again, per the above, it will do wonders for your mental health not trying to work all the hours in the day to prove you're valuable.
Be flexible and set expectations thus. If you have school runs (remember those?) then do them. If you need to hang the washing out, do it. You will find this again helps your mental health because it's a diversion from the grind. Before you start to feel guilty, remember that even at work in and office you have "dead time" - time spent at the watercooler, or otherwise chewing the fat.
Your IT is usually set up just how you want it and because you're not waiting for someone to open the dial-in conference bridge, work out how to get the big screen/projector working etc that meetings open - and close - much more efficiently. Not always, granted, but mostly.
Enjoy the fact that, if you're following the advice from point 1 and working contracted hours, you can even be flexible in your start and finish times because you're now not sitting in traffic for an hour or more each way to and from work getting worn out by it.
Set boundaries - both with colleagues and bosses but also with family. It took a while before my then wife understood that when I am working from home, I am working and no I can't just go shopping or for a long walk at the drop of a hat. Make sure your bosses and colleagues don't expect to be able to get a hold of you 24/7. Try to remember they do not own you. I had one boss who had a go at me because "...well I work 07:30 to 23:00 why don't you work longer?" he did not appreciate my response that I'm contracted for 40 hours, I am paid for 40 hours and they get 40 hours and I, like him, have a family. But unlike him, I am not a moron.
Remember to take a break occasionally and walk away from your desk. Again, you'd tend to do this at work, so do it working from home.
You will have bad days and good. Don't beat yourself up about it.