Depending on how fragile the party scout is, and other factors, my advice will change. I like to stay at least 60 feet ahead so that the party essentially gets a +6 to their stealth check due to distance.
Disclaimer: I understand the +6 is really applied to the perception DC, not to the stealth check.
What are these other factors I hinted at above?
How stealthy are you? If bad guys likely need a 15 or better to notice you if you roll a 10 I'd say that's good.
If you're not that stealthy I'd drop the distance back to 30 feet unless you feel like you're not easy to take down.
How good is your perception? If you don't have really good perception I'd stay within 30 feet so you don't get ambushed and killed while the party is trying to catchup to you.
I know you mentioned rogues, but slayers, monks, rangers, and so on can also be stealthy. So I'd also look at how good your AC is, and how much punishment you can take. If you're fragile stay within 30 feet.
My current scout has a good(not great perception), but I have pretty good stealth, good AC, and I can take a hit before falling over.
PS: This assumes long hall ways. I would never suggest entering a room by yourself.
This also assumes that your GM has no qualms about allowing you to you suffer for your decisions. If he's the type to softball things then you can take more risk.