Since you bottled in Grolsch bottles, that makes your life a LOT easier in this situation. I would let them carb for one week. Chill one bottle for 48 hours, and sample. Check for overall carb level and gushers. Remember that it is normal for young beer to act like a gusher if it is still in the process of carbonating. If the bottle gushes, or if the head is HUGE, but the beer itself is still flat, or not overly bubbly, then you are probably OK. This is normal for beer partway through the carbing process. The yeast has made a bunch of CO2, but it has not been absorbed back into the beer yet. If it gushes, and the beer itself is overcarbonated, then you will need to vent pressure.
This can be done by spraying the tops of the bottles with a contact sanitizer (like Star San), waiting one minute, opening the top to release excess pressure, and re-capping. Since you used Grolsch bottles, this is as easy as releasing the metal band, lifting the lid, and then immediately re-closing the bottle.
If your test bottle is still completely flat, check another one in 2 to 3 days. Keep checking every 2 to 3 days until you find properly carbonated or over-carbonated beer.
Also, it would be a good idea to put your bottles into a large plastic tupperware tub, heavy trash bags, or some other containment device, until you are more certain that you are not storing a case of beer-grenades!
"Give a man a beer, and he will waste an hour. Teach a man to brew, and he will waste a lifetime!" Bill Owen