I missed the supply voltage. Yes, add a 12 V Zener diode across the 555 power pins and feed it with a 1 K resistor. Also, I strongly recommend changing to a CMOS 555, such as an LMC555. If one end of the relay does not have to be connect to GND, you can re-arrange some things and delete a bunch of parts:
1. Change the MOSFET to n-channel
2. Delete R6, X3, R10, Q3, R7, R8, and R9.
3. Connect 555 pin 3 to the MOSFET gate.
4. Connect the relay between Vcc and the drain.
5. Connect the source to GND.
ak