It's not better to do it so and I'll try to explain why. Probability of receiving a gate part (or multiplier) is 13%, that is 13/100. Thus probability for something else is 87% (87/100).
How it is when you use x2 multiplier immediatelly after received?
For this you have to receive 2 times gate part in a row, so the probability is (13/100)*(13/100)=0,0169
How it is when you use x2 multiplier later?
If you use the multiplier the 2nd spin after received, the probability will be (13/100)*(87/100)*(13/100)=0,0147
With every spin without using the x2 multiplier, you have to multiply the probability by (87/100).
I attach a site where it's explained better:
[Only registered and activated users can see links. Click Here To Register...]