Great tour! We went to Ijen and Bromo in October 2017, one day notice before the trip was not a problem 🙂 Guys are flexible as for the route – picked us up at our hotel on Bali, and then drove to Surabaya airport. I liked very much that they offered several options as for accommodation during the trip (it takes 3 days and 2 nights) – cheaper and more expensive one. Guide (Andre) is very nice and positive guy! He told us lots of interesting things about volcanoes and star sky, also showed good spots for making photos.
Overall, there were no problems at all – guys (Henry and Andre) are friendly and polite, meetings are always on time (even at night – you have to get up really early to meet a sunrise) – we never had to wait for them.
If you plan to visit Ijen and Bromo, I can definitely recommend Java Adventure Trail!