Strange behaviour of ne555 + pmosfet circuit
You should add a resistor from VCCIN to GNDIN to discharge the capacitor C2 more-or-less fully when power is removed. 
It's been a long time since I've seen an NE555 let alone played with one, but check that the output pin is going close enough to the positive rail with your 11K pullup to VCC. If it doesn't get within 1.5 to 2V of the rail the MOSFET can slightly turn on. The CMOS versions do not have that problem, but the NE555 is the original bipolar design by Hans Camenzind (RIP).