Aww, welcome to you and your sweetie from Joey and me. It is so awesome you recognized his need for patience, and gave it to him. He sounds like a real darling.
Have you tried hand feeding pellets? To get Joey interested, I hand fed Zupreem fruity blend as treats, talking them up in an happy voice. He soon learned to love them, and they are still his favorite 'treat'. I don't have the heart to tell him they are healthy.
Any time I have introduced a different brand, I have hand fed them and made them seem special.