Let's clarify a bit, which battery are you talking about, the 1.5V battery connected to the MOSFET or the 3V battery connected to the 555?

Assuming the latter, I believe you can solve the problem by adding a power-on reset feature. Take a look here: http://www.kpsec.freeuk.com/555timer.htm#monostable and look at Power-on Reset or Trigger. And I apologize, I read Tracecom's replies but didn't realize this link came from tomega3 originally.

Disconnect pin 4 from 3VDC and put a 10kΩ between pin 4 and 3VDC. Add a 0.1uF ceramic capacitor between pin 4 and GND. When you apply the 3VDC to the circuit, the reset pin will be pulled low momentarily because the capacitor will act as a short to ground until it charges up (within a second or so if that). During this brief period, the 555 will be in reset mode which will keep the output off.

Let us know if this works out.

I was thinking the same thing. Should have used that in my project.

 

elec_mech

Let's clarify a bit, which battery are you talking about, the 1.5V battery connected to the MOSFET or the 3V battery connected to the 555?

Your latter assumption is correct! Its the 3.6V battery connected to the 555 timer.

elec_mech

Disconnect pin 4 from 3VDC and put a 10kΩ between pin 4 and 3VDC. Add a 0.1uF ceramic capacitor between pin 4 and GND. When you apply the 3VDC to the circuit, the reset pin will be pulled low momentarily because the capacitor will act as a short to ground until it charges up (within a second or so if that). During this brief period, the 555 will be in reset mode which will keep the output off.

Will this change the function of the output duration when pin2 is triggered.I only need to shut off the LED when i power up the 555.

 

Nope, this will not affect normal operation. The resistor will keep the reset pin pulled high once the capacitor charges at start up.