It's possible.

The default position of a Boyer ignition is full advance and it requires battery volts in order to retard it. It then progressively advances as revs increase.

This causes the unfortunate side effect of vicious kick-backs if the battery has dropped below about 9.5v and it destroys electric starters on the 850 Mk3 - Using the electric starter pulls available battery volts down so starting is on full advance which causes a backfire that tries to turn the sprag backwards.

Thanks Ian and Rick.

The possibility of starting retarded have not crossed my mind... interesting.
I have contacted the manufacturer, and he sent me what I have already known:
When setting the ignition I need to bring the engine to the timing point,
And then fasten the electronic magneto when the electronic sensor/trigger
Is in parallel position to the magnet which triggers it.

What I understood, and may be wrong, is that in that point the magneto
Would spark, and from this point and on, there is only more advance...
The good side of the this electronic magneto is, that much like the original,
It does not require any battery.

I asked the manufacturer again, only to be sure...
Lets see what he will say.

Cheers,
Noam.