Explain why Tom gives up his first (37-year) plan to free Jim so easily

The next day, they steal some tin plates and a brass candlestick for Jim to write with. They also finish digging the hole and make it possible for Jim to crawl out. Jim wants to escape immediately, but Tom then tells Jim all about the little things he needs to do first, including writing in blood, throwing the tin plates out of the hut, etc. Jim thinks all of these ideas are a little crazy, but agrees to do it. Tom then convinces the man who brings Jim his food that Jim is bewitched and offers to heal him by baking a pie, in which he plans to conceal the sheet ladder.