In my humble opinion, that's a darn good guess. I'd have suggested 3-5 days. However, if the best before date was almost expired when you froze the tofu, that number could be less.
Oh, and trust me, when tofu goes bad, you will smell it. It has a pungent sour smell when it goes. I'd still recommend food safety guidelines, when handling any perishable food, but don't forget your nose, smell is a pretty good indicator.
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