Too late to take BBT?

Is there a window to take bbt after waking up before it’s not accurate enough to take anymore?

Usually, I keep my thermometer under my pillow. The way I sleep, my hand usually runs into it in the morning, before I’m fully awake, but it reminds me to take my temperature (I’ve got one that syncs with an app, so I usually just need to check and make sure they got synced, rather than remembering to note down the temperature, at least).

This morning, that didn’t work, and I’d gotten up to run to the bathroom before I remembered. Wasn’t fully awake (maybe up a minute or two), but definitely more awake than usual. I decided to take my temp anyway (got back into bed in an attempt to get things a little more consistent) and recorded it. There was a spike of about half a degree between my temperature yesterday and today, but according to glow, I should have ovulated yesterday anyway.

Just wondering what people’s opinions are about when it’s too late to take bbt, and when you go ahead and do it anyway, even if it’s a little later. What’s your sign that you missed the window?