Methylcobalamin is wonderful for cats with neuropathy. Bandit never had neuropathy, but Syd (a good friend's diabetic cat) had severe neuropathy and could not walk more than 2 or 3 steps at a time (nor make it to the llitterbox). We saw good improvement within 2 weeks of starting the Methyl B12, and today (about a year later) Syd is fully recovered and in remission, and sprinting around his house like a crazy cat.
You can start Methyl B12 immediately--in fact, it tends to help with regulation because it helps reduce the pain from neuropathy, and pain can keep BG high. Exercise will also help with recovery--you want to get those limbs moving. Obviously, you're not going to see the cat sprint around the house right away, but encourage him to walk from one end of the house to the other, or up and down the stairs (perhaps with diabetic safe treats) a few times a day.
The zobaline tablets are fine, but they are a bit overpriced and a bigger pain to administer than just the Methycombalamin capsules, in my opinion. There is nothing that makes zobaline better for cats than regular Methyl B12 (except for the packaging). I got these capsules on Amazon:
http://www.amazon.com/Vitacost-Vita...5000/dp/B0046HLOTY/?tag=felinediabetesfdmb-20. For $4 more than what you're paying for the zobaline, you get 40 more doses. And you don't have to crush anything because the content of the capsule is already in powdered form.
You just open up a capsule and mix it with food (once a day), and it works great. The recommended dose for cats is 3-5mg (3000-5000mcg) per day. Since you can't overdose Methyl B12 (the cat will pee out any excess) I personally think it's best to go with max dose because it
could be more effective, and there's nothing to lose if it's not. But really, it's just a matter of preference, and either option is perfectly fine.