The actual troll raid event won't start happening until after you've defeated the Elder though, so for now you can use the local ones to get used to how to how to handle them.

Make sure to leave enough space between your palisades and structure walls (roughly 6-8m) so that the few attacks that do manage to clip through them (the log swinging troll in particular) do minimal damage to the inside structures until they can actually break through the outer defence.