BBT Question

I made an account on FF yesterday, and I am curious as to whether or not I absolutely have to temp in the morning, or if I can just do it in the evenings before bed. Will it matter? I mean, just as long as I do it around the same time every evening?

it matters. You have to do it in the morning for it to be accurate. Studies show that the temperature in the morning is usually higher than any other time of day (assuming you do not have a fever).
It's ony accurate if done in the morning, before you getup and start moving. Has to be done immediatly after waking up.

Has to be done first thing in the morning before you even get up.

yes, it has to be first thing in the morning, preferably before you even get out of bed and preferably as near to the same time as possible every day.

Otherwise it is inaccurate, as your temp varies a lot during the day and when you are tracking BBT, you are looking for very subtle changes.