Ashman probably said it best...watch your oil usage.
Another question is whether the leak is near the front or the rear of the engine? If it's near the front, then it's more likely the timing cover seal, not the head gasket.
Otherwise, oil leaks near the rear of the head is likely the head gasket. Yes, it will only get worse, but you can buy a little time, just by monitoring oil usage and add when necessary. At this point, there is no real engine damage, but rather an annoying oil leak.
Oil in the coolant reservoir indicates a total gasket breach...at that point, time is up. Driving any further will result in coolant overflow from the excessive cylinder head pressures manifesting themselves into the coolant path.
Continuing to drive with an overheated engine will result in a warped head...which is much more expensive than just a gasket.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car