Looks like this ain't necessary

Also, the condition was the opposite of what it should have been.

src/converse-muc.js

@@ -326,9 +326,6 @@
                     );
                 }
                 const promises = [_converse.api.waitUntil('roomsAutoJoined')]
-                if (!_converse.allow_bookmarks) {
-                    promises.push( _converse.api.waitUntil('bookmarksInitialized'));
-                }
                 Promise.all(promises).then(() => {
                     _converse.api.rooms.open(jid);
                 });