What I decided to do is start in HV mode for the first few miles so it could warm up slowly, which helps with the heater as well. Then switch to to EV, and I didn't need the ICE again for the remainder of the trip.
Sounds like a plan, then again you have all winter long to try different strategies. Realistically even if you don't touch any buttons at all and just let it use up EV and let it automatically switch to HV for the remainder you will be fine and will likely get nearly identical overall efficiency. That is how many people drive their Clarity which is fine. Others (like me) are button pushers who just can't accept that we are not needed in the process and so we insert our fat thumbs into the proceedings
But seriously the points about seat heating vs. resistance heating are valid so the seat heater is one button you will want to push at least while in EV mode if it will allow a lower set temperature and thus less use of the resistance heater. But no need to go beyond what you are comfortable with. Also as you mentioned it can be worth thinking about what part of your commute you will run ICE, timing it (if possible) that you are in HV mode during periods when you need a lot of cabin heat. That may for example be more when you are leaving work if your car has been sitting outside in the cold, as compared to the morning when your car has been in a garage all night, even if the garage is unheated if it attached to the house it will likely be warmer than outside. Also you can experiment with doing preconditioning in the morning either via the app (easier with L2) or the fob. No need to wrack your brain about all of this but since you are asking, those are some things you can think about as you try different strategies this winter.
Also a lot of people including me have one general preference which is that if we know that at least some of the miles will be in HV, we prefer to use EV on surface streets, basically anywhere that acceleration is often needed, and HV when cruising for longer periods at steady speed (like on the highway). This is because the gas engine can be somewhat noisy at times when accelerating from a stop light. Not objectionably so, but in comparison to EV which is silky smooth. Whereas at steady highway speeds I hardly notice the engine. Just personal preference, I really don't think it makes much if any difference in efficiency.
Also being geeky
I like to see the "gear" icon come on in the energy display which only happens at steady speeds in HV mode. It is when the gas engine is essentially directly connected to the wheels, or at least more direct than at other times when it is only acting as an electric generator. In fact Honda calls this mode "Direct Drive", although you often hear people refer to it as gear mode because of the icon. We assume that ICE is more efficient in Direct Drive mode than working solely as a generator or they wouldn't have bothered installing the physical hardware which makes this possible. Although I am not aware of any data showing how much more efficient it is in that mode. So it's not really worth trying to make it go into this mode, I'm just pointing out that it often does when you are in HV mode at steady speeds above a certain mph (it's not an exact mph range).
Most of the 60 mph freeway portion of my commute is relatively flat but there is a specific three miles section that has some undulating hills, actually they are overpasses where the freeway goes over surface streets (instead of other way around). During summer the car was just as quiet when going up those "hills", but as the temperature is dropping I notice that ICE can be a bit noisy when climbing those overpasses. So I might start switching momentarily to EV during that section.
Another trick I might try for that section is something called HV Reset which is double geeky
It's not a documented feature, but as I mentioned in my previous post the EV range often drops a mile or two when you first select HV mode (as it does at other times as well) and what you do is while the EV range is down before it climbs back up again from engine charging, is you momentarily turn off HV and then turn it on again. This resets the HV target to the lower value, so it will try less hard to charge back up, and is thus less noisy. I heard of this trick from people who do a lot of driving in the mountains so it should work on my trivial little overpasses.
Again the above is in case you think you may want to experiment with the different modes, but it is purely optional and most certainly not necessary, it's just a matter of personal preference.