Well, you can do a couple overnighters as a shakedown and hope for the best. Not my recommendation for someone in his 60s with no self supported touring experience. A week long trip or two will do wonders for sorting out any issues. You may find your saddle is unbearable after a few days. Or may develop saddle sores. Or find your bike fit is leading to knee pain. Just to name a few. You could easily do a week trip to the Gulf Coast in the spring and gain valuable experience.