Congrats on coming back to bowhunting!

A good rule of thumb is 1" of group for each 10 yards of distance for most hunting. In other words, you should be able to obtain 2" groups at 20 yards even with an older set-up (with practice).

The release will improve your accuracy a lot. If you have a local bow shop, it would be wise to let them inspect your bow. They can make sure the string/cables are in good shape and perhaps give you a hand with setting up your rest/sight.