Fire Particle: First Shoot Too Big

Hi, I'm using the built-in fire particle to create the fire inside of a lantern. I've scaled it using the Ellipsoid particle emitter, and it works perfectly. The only thing that I'm not able to understand is that 1st shot is always bigger than the values I've set.. This is really a big problem because in the 1st shot the flames appears outside of my lantern model..

What I'm doing wrong ?

Thanks a lot