I have come across the words "antaǔ" and "post" for "before" and "after." These words though, also mean "in front of" and "behind." Can they also be used for time?

If I want to say, "I brush my teeth before I go to bed," do I use "antaǔ?"

and if I want to say, "I go to bed after I brush my teeth," can I use "post?"

Can "antaǔ" and "post" be used with regard to both location and time?

"antaŭ" could be used when you want to say "ago".
i.e.: Mi skribis leteron al li autaŭ du jaroj. (two years ago)

"post" as "in".
i.e.: Mi skribos leteron al li post du jaroj. (in two years)

If you want to say before or after with a complete sentence or a verb (infinitive), then you have to use "antaŭ ol" or "post kiam", which is regarded as a conjunction.
i.e.:
Mi skribis leteron al li antaŭ ol mi venis al Usono.
Mi skribis leteron al li antaŭ ol veni (al Usono).

Arktischgeist:Can "antaǔ" and "post" be used with regard to both location and time?

Yes.

I brush my teeth before I go to bed → Mi brosas la dentojn antaŭ ol mi enlitiĝas.
I go to bed after I brush my teeth → Mi enlitiĝas post kiam mi brosas la dentojn.

As lunaris mentioned you need to add "ol" or "kiam" if you are joining to a verb or phrase containing a verb, in order to make it a conjunction. When antaŭ or post goes before a noun you can (and usually should) use them without ol: "Mi brosas dentojn antaŭ la enlitiĝo" would be another way to phrase your example.

Note however that you can still use "ol" even when "antaŭ" is going before a noun, if a verb is implied: "li venis antaŭ ol mi [venis]". This can sometimes help make it clear you're talking in a temporal sense, rather than spacial.