Figuring a cold lasts about 7 days and incubation is 4 days, I'll lay low for about 10 days before going, and wear a straitjacket and mask on the trip until I get out of cold country.
I'm sorry, I do not believe in Vit C, Echinacea, zinc or other cold preventers. I've taken none of this stuff and I haven't had a cold for about four years either. I have had about 20 times when I thought I was getting a cold.
I see colds as especially vulnerable to placebo effects, since
1. Often you think you're getting a cold but you don't (but not because of anything you do)
2. There's a lot of random variability in whether or not you catch a cold when others around you have one.
3. If you've already had that "variety" of cold, you won't get it.
4. Once you no longer have preschool or school kids, your risk of cold goes down dramatically
So all of this leads to a lot of supersitious behavior. I know many people who swear by echinacea, but if there were any effect there, it would have been seen in some well-done studies by now.