When I have carefully checked all proofs and preferaby have either have a rough latex draft of the proofs or reliable handwritten notes. But I am cautious. If you have not checked something carefully you should make it clear that you believe you have a proof but details need to be checked.
Venue doesn't really matter.
If I think that others are very close to proving the result I would probably make slides available with the date of the talk to cover priority.
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