I would wait 24 hours to make sure you get full statistically updates, thats what I do. I do notice if I push the date ahead the last full update I'll sometimes get some results, if you want accurate results wait 24 hours.
It's weird how my Analytics stats don't match up with my 1and1.com stats. 1and1 shows a whole bunch more. Who's right? Google or my own host?
Analytics takes 48 hours, but mostly (usually) 24 hours. I think 1and1 uses AWStats, right? Regardless, AWStats shows much more than Analytics does. Most prefer it.
1and1 probably shows you server logs, the server logs are more accurate. Some people in their haste also block Google ads, stupid but yes that's why some users may not be tracked. So server logs show everyone regardless. Also server logs show robots - while google analytics does not because most bots will not execute javascript code or images and thus go invisible to analytics but get picked up by server logs. So your server logs are generally more inflated and do not represent an accurate depiction of your traffic (remember not all bots are good, and if you're listed on Google - chances are very likely that some of the bad bots could be visiting your site - possibly scraping your content, looking for e-mail addresses, etc). So Google analytics is better in terms of showing # of real visitors (better to have a low number and have higher traffic, then higher number, but lower traffic). Anyways, the main thing is that it depends - if you're going for bandwidth/bots/visits/page loads - then go with server logs - but if you want real-world data of visitors go with Analytics. Personally server logs are good for script and back-end issues, while analytics is excellent for determining and investigating your visitors. edit: also server logs are generally live - they show you a second-for-second stats. While Analytics updates every 24 hours, but you can get some early data by clicking on the current date which will show some rough stats (it updates every 12 hours but this data is mostly outdated by a few hours by the time its accessible to you in your analytics panel).