The Guide suggested starting by getting used to swallowing up to a natural mouthful, which Mika had already done. After that, it suggests something compressible, but naturally larger then the pred's mouth. Like a kid size hamburger. The point here was to learn to force your way around softer, jutting parts of prey while also training your throat and jaw to exceed what most think is the human limit.
That made sense to Mika. After all, using the hard, rough surface of an apple right away, like the stories online, would immediately cross a point of no return, where either you got it down or you chocked to death, with no ability to smush it or try to change it's shape some. The small kid size hamburger was about the same size, but she could break it into 3 ready made parts if she had to, and could compact it to be even smaller. Much better.
Mika took about a week to before she managed to swallow the entire thing all at once. She was surprised how quickly her throat was getting stronger, feeling it as it firmly crushed her meal while she ate. The next suggestion in the Guide was to find something a bit smaller than the hamburger, but very tough and resistant. It suggests a chicken leg, swallowed lengthwise, bone and all. This gets the predator used to the way that most meals are thinner than they are long, don't have much give for most of their length, and further gives them experience in dealing with bones.
Mika found this extremely easy, succeeding on her second attempt. However, she soon found that even small and weak bones are very strong against digesting. The next day's shit was hell on earth. She didn't give up though. Instead, as the Guide suggested, she started to swallow chicken wings, then thighs and finally breasts. By the time she'd swallowed a couple chicken breasts whole she could digest the chicken bones reasonably well.
Then the Guide gives what Mika finds to be an odd suggestion. Swallow an entire plate of pasta or spaghetti in one long chug. The Guide is extremely specific that it must not, can not, be done by taking in a huge mouthful. You have to appear normal while sucking it down continuously. The Guide says that it is to teach your body how to breath while swallowing, an ability that is absolutely necessary to continue! After all, swallowing even the smallest child will require up to 5 minutes, which is utterly impossible to hold your breath for.