Congratulations! The 835 is a very reliable shotgun and is used by very many hunters. It just works to kill turkeys. I'd recommend that you "deep clean" that barrel/choke before you pattern it. I've had many readers who have improved patterns dramatically with just a good cleaning.
If yours has the factory turkey choke, I'd try it before even considering another turkey choke. Many times they work quite well and you don't need anything else.
will get you to an article about "deep cleaning". It's a process that just works.
I'd also recommend that you consider using 3" shells with that gun even though it chambers 3.5" shell. Many times, the 3" shells pattern better, they cost less and they certainly kick a lot less.
Good luck in the spring.