In entry #292, you may recall seeing these two expressions:
Merci pour tantôt.
Désolé pour tantôt.
In both cases, tantôt refers to a moment in the recent past. In other words: thanks for earlier on; sorry for earlier on.
Another example of tantôt:
Il nous observe depuis tantôt.
He’s been looking at us for a while.
You’re in luck — you can hear this sentence in the clip Rencontre du deuxième type, which has been providing lots of good material in the past few entries!
Tantôt can also refer to a moment in the near future. For example, you’ll often hear the following expression when people are saying good-bye to each other for the moment:
It means something like “see you in a bit” or “see you shortly.” It’s equivalent to à tout à l’heure or à plus tard. The next time you’re saying good-bye to a friend whom you’ll see again later on the same day, you can say à tantôt!
By the way, the expression à tantôt is also used in Belgium in this same sense, so I guess we can’t say that it’s québécois! Maybe we’ll have to call it an expression belgiquébécoise...