When does the Magnus force take effect?

[G15]

Hey.
I'm not great at physics, so apologies if I'm missing something obvious. This isn't homework, I'm just interested in the topic.

I have a particle in 3d space and have an impulse applied to it. This impulse pushes the particle in the air and I have drag applied to it. Now, I'd like apply a Magnus force to the particle. When does the Magnus force take effect? Is the effect applied immediately or does it only take effect after a certain amount of time? If I was to program it, would I constantly calculate the Magnus force after the initial impulse or after a certain time period?

Thanks for any help.

 

[torquil]

The Magnus force acts continuously on the object while it spins and moves relative to the surrounding air.

http://en.wikipedia.org/wiki/Magnus_effect"