Yes, Jaskier may go! At the time that Jaskier asked, the arrangement with Solvunn had not yet been made, but once it has she will inform him that he can proceed.

Rowan March and Isar Hart will remember Jaskier. The former will recall Jaskier due to his song about Lyfbringr while Isar will recall their conversation in Nocwich. They'll be quite cordial with him with the typical Solvunn warmth.