First of all your photo has to meet the criteria:
http://www.panoramio.com/help/policies_legalities
When your photo is mapped and big enough the photo is reviewed. Recently I’ve seen reviews 10 minutes after uploading up to 8 days, but it can take longer. A blue compass appears under your photo on the photopage.
>From that moment you have to wait for one of the next data transfers to Google Earth. Those are normally once a month. That doesn’t mean your photo is in the next transfer but can be in the transfer a month later. So 6 weeks to 2 months after upload is normal, everything under it is super!
Photos are visible at very low altitude in the beginning!