Refer to this image...
the way you describe carbing, will take 2+ weeks to carbonate. (the green line)
If you want to carb in a week, you should try this procedure (Blue line)
1: hit em with 30PSI to seal the lid
2: leave 30PSI for 2 days
3: disconnect gas and bleed pressure in cornies
4: reconnect at 10PSI for 5 days
that should get you a good level of carbonation in 7 days. Some people like to shake them to carb faster, but I have always overcarbed (Red line) when i try that.
As long as your kegs have no gas leaks, you should be fine to leave them and not need to hit them with more gas. Mabye switch the gas back to the original 4 the day before the party just to be sure.