While I was searching I found this link someone posted... Its a calculator which adjusts your bbt to a different temp if you tested earlier or later than usual. I put my temp where I took it 4 hrs late and it put it to .2 degrees higher.... Very curious!
https://www.whenmybaby.com/basalbodytemperature.php
I find that unless my sleep is SUPER restless (and that actually lowers my temp... I think my agitation combined with being drained taxes my adrenals and thus lowers my temp), if I take my temp after the longest stretch of sleep (usually that is when I first go to bed then first wake up, or 10ish to 3ish), that's most accurate. So I just use that temp but record the time. FF and most apps figure that in. OR... I might just increase the temp by .1 or .2 higher if it's during O time and I *need* to have the most accurate temp. possible. On a super bad sleep night, unfortunately I just have to average out the temps I take throughout the night, each time I am going to get out of bed, but then discard it. I use OPK and check CM, so between those FF can still pinpoint approx. O. Good luck and sorry for the long-winded, possibly confusing answer. Short one: no, don't use the # that adjuster gives you - if anything, record the temp you take early or late and record a temp in the middle of that temp and that site's suggested adjustment, which is always extremely lower or higher.