Dear Sir, They are all wrong but 1 is almost right. Just add "it" at the end, and it will be a good first conditional sentence. The other two sentences are nonsense because their grammar is wrong.
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Chanakaranathunga1. Once you give it to me, I'll do it. 2. Once you gave it to me, I did it.1 and 2 as shoI'll do it3. Once you gave it to me I have done it.