To piggyback on a few other comments here, yes, step back and don't attempt your entire shave with this new blade. Do the easy bits with it and use your feather for the rest, expanding your range as you get more comfortable with the new set of angles etc.
Here's some stuff I wrote a couple of years ago about calibrating a controversial sharpness test, whose name or acronym I won't even utter in this fair thread. But explore it with a feather blade and again with your Hart. It will give you a sense of how much wear and tear a single shave causes to a fresh edge, or how much more you can degrade a tired edge. It'll also probably show you that the feather blades are insanely keen. Take up Shooters offer of a honing... I bought one of my favorite blades from him years ago and it arrived with a wonderful edge. And believe everyone who tells you not to strop your blade when it arrives from its honing. If you muff the stropping then you'll never know how good it can be.
For me, a properly sharp edge shaves when I only apply enough force to remove the lather. It feels like magic. I have enough experience now that I can push a tired edge through an effective, harmless, but uncomfortable and unmagical shave. But you can get that second kind of shave anywhere... we choose this slower, more contemplative approach to enjoy the feel of doing magic.
Good luck and best wishes.