Time after HIM for an FTP test

I'd try to execute a few hard workouts before the FTP test. They'll help you decide if you're really recovered and you might not be used to such an effort after doing and HIM.

You may not get accurate results anyway if it's your first time doing one, it can be tricky to get it right for the first few.

I'd do what Ben says, a few hard workouts to give you an idea if you really feel ok and then go for it.  Use the numbers you get from it for a few weeks and if the workouts you do based on the results don't seem right (too easy or too hard) then re-test.

Well, you didn't fade at the end or have a bunch left in the tank that let you jack the power way up so I'd say it's a reasonable result to base some training on.  You'll know once you do some workouts whether or not you need to re-test soon.  

I'd say you did really well for a first attempt.  Don't compare your numbers to others, just focus on your own, do the work and you will get results!

Yeah, that seems decent for a first attempt at it. I could see it smoothing some with a little more practice, but not really glaring issues in this.

And to add to what I said earlier, I get the almost puking feeling more easily when reintroducing over threshold work after not doing it for some time. It might jump up over the next few weeks simply from that. It's your body just getting used to working up there again. Still, this should be good enough to start.

Are you using a Garmin?  If so, does it not ask you to calibrate it when it detects it?

Definitely not bad for a first attempt!  It looks like you started a little conservatively (a good plan), bumped it up a bit five or so minutes in, but then you did fade a little between (what appears to be) 10 and 15 minutes, and then really buckled down for the last five minutes.  But nothing glaring -- I remember for my first attempt, I way overestimated my ability for the first five minutes, pretty much died, soft pedaled for a bit, tried pushing again....lasted a few minutes before I finally gave up.

Once you know roughly where you are and have a good strategy for the test, they become a little more doable....but if you don't start thinking you want to quit or you might puke, you're probably not doing it right.  The only thing that keeps me going is that if I quit 10+ minutes in, I know I have to do it again and have already tortured myself long enough that I might as well finish it out!

Yes, it should do an auto-zero when you coast for a few seconds.  On the trainer I usually do it once around 5 mins (while turning on some fans) and then again around 15 mins (when I open the window).  

I don't *know* that it does the auto zero as there is no indication as such, I'm basing it purely on P2M saying that's what happens.

Flat-landers...  ;)

I would do a manual calibrate on the 920 at the beginning of the ride (not sure how you do that, Marc or someone else with one would know) and then at some point early in the ride just coast for 5 seconds.

Just an FYI for the calibration, I have a P2M and use a Garmin 500.  If you have a HR monitor paired to the Garmin, it will not calibrate the P2M unless you are wearing the HRM.  No idea why, but it will sit in limbo indefinitely until it detects the HRM.

Not sure if this is an issue for the 920xt.