i am a horrible sleeper (and no LO to blame!
) so since i can't always rely on 3 hours of solid sleep before temping, i try as hard as possible to take them at the same time. if i take it with less than 3 hours of unbroken sleep, i always check "sleep deprived" and don't discard any temps because i think FF knows when you check "sleep deprived" that the numbers might not be reliable and factors that in when it tries to predict things. even if the time is a bit off (aka: sleeping through my alarm or waking up 30-60 minutes before my alarm) i still take it and input it.
FF seems to be set up in a way to take all of these things into account; i think any data is better than no data, so i keep it all.
i started a thread over here: https://babyandbump.momtastic.com/ttc-groups/2204607-any-bad-sleepers-temp.html if you're interested in hearing other people who temp but don't always sleep so great.
good luck!