You need a balance of both
Doesn't really answer the question of what the balance is, I assume that as time goes by it will be less painful to spend time standing/walking (hopefully that happens very quickly) At what point do the vast majority of ppl manage to spend more than 10 mins out of every hour on their feet? At what point can you spend 15 mins standing/walking? I was told I could not walk the 1/4 mile to the drs office at 4 weeks post op. which is literally a ten minute walk.
My choices are sit on bed, lay on bed, sit on hard kitchen chair, no arms-why would I need arms on the chair? there aren't any on a bed, so how do ppl get out of bed? I'm not trying to be difficult, this just doesn't match up with the videos of folks who are recovering from TKR (there's a LOT of them) and it doesn't match up with what I've read on this forum either. The vast majority of ppl say they were too tired and dopey/drugged to do much more than sleep off and on for the first 2 weeks for sure and a huge percentage of those said the same about the next 2 weeks or more. At least 2 ppl I know slept in a recliner day and night for a month (and were on oxy for that entire time)
I am not one to lay around much. I sleep 6 hrs at night. Hopefully the doctor's nurse will have some handout on how much to elevate, how much to ice, how much to sit, etc, for avoiding blood clots, sitting on a hard chair for long periods seems pretty risky. Seems like having your feet up even if you need to be laying down in bed, is a much better option. Obviously you're doing ankle pumps and heel slides and whatever else they want you to do.
I do these all the time now (just for muscle memory and to be in the habit)
There are ppl who have no living room furniture. Would you like a photo of my place?

I still think I'd be safer on the floor, but apparently getting up off of it would be hilariously difficult. But if you fall.... you're going to have no choice but to figure it out. Seems like it would be a good idea to figure this out in advance. I know at least 4 people who fell after their TKR (not ppl on the internet, ppl in real life that I either bowl with, or play cards with, or do yoga with etc) One broke her foot and shattered her pelvis-ended up with lots of hardware. Another one had a fractured femur, and the other 2 were pretty badly bruised but otherwise ok. Falling after a TRK seems to be fairly common.
I was in a full straight leg long cast (covering my entire foot to the very top of my thigh) for well over 6 mos. I was able to get up off the floor. I could not put any weight on my right leg, the cast was not a walking cast (I only had a walking cast for the last 2 mos) I did fall flat on my back once in the snow (was a bit drunk) and needed help but only because I was drunk and laughing too hard to figure out the steps to take to get up. This is the only frame of reference I have. I must try splinting my leg to see what I'd need to do to get up. Admittedly I am 50 yrs older now LOL but I think with a chair nearby this should be do-able. I'll try it tomorrow, that should be good for a laugh at least.
Your leg must work just fine right after surgery if you are able to get up and walk to the bathroom and climb stairs, you must be able to bend the operated leg at least a little which is more than you can do with a full straight leg cast. In the videos of people in the first days and weeks after surgery they are walking around and no one is moaning or groaning or grunting in pain (I always make funny noises when I'm in pain so it seems odd to me that these folks are silent) so I'm guessing it can't be all that painful. They also walk pretty fast. People who have a TKR disappear for a full 6 weeks. Every. single. one. I must know of at least 50 people who had this surgery but I've never been able to see any of them in those first 6 weeks. That's kind of scary you know?
Met a guy at PT who was at 6 weeks and wasn't using a cane, but he limped on the operated leg and on the bike, he just did a half a revolution and then went backwards. I sat right beside him on the other bike and he never got the pedals to go around once. All of this is very confusing to me. He didn't appear to be in a pain. His knee was not especially swollen, maybe a tiny bit bigger than the other leg (he was in shorts) IDK what to think. He said he didn't want any company for those first 6 weeks, but he does have a wife.