It’s at least 7 sessions unless you’re constantly dropping hints. Parties are stupid, I found the map in the goblin fort but I don’t think we ever looked at it.

To be fair we did have two goblins tied to ropes that we were using to check for traps.

It developed a lot, for example had a reoccurring character from the Goblin encounter called Dibb, he’d always escape. Every session just added more and more lore and eventually ended with them having their own HQ in the abandoned village where they faced the Dragon.