Probability Q Involving Sampling

Please, I'd like to know how to calculate a probability based upon sampling.  Specifically, I'd like to know the frequency of needing to check back with /sci/ about the proof of the existence of this "giant alien space monster" (YHWH, Allah, etc.) ... when no proof has ever been collected in 5000 years.

Based upon the probability of success, how frequently should I check?  Every week?  Year?  Century?  Millennium?  Never?

Jeepers, let's have a swell time then

Most assuredly, I am.  Aren't you?  Hot damn, let's get our chan on!