Flammability Magnitude and Incinerate/Flameblast

My friend has been playing Blackflame covenant with Incinerate and Flameblast as her main abilities. We've been trying to re-arrange some of the points on her tree to squeeze out more damage, but I need some more info about Flammability magnitude. We already know that stat priority for BFC fire damage goes Flat/Extra damage>Ignite Magnitude>%Spell damage/Chaos

Given incinerate's wording of 'Ignites as though dealing X damage' I mistakenly though flammability wasn't necessary at all to make it work, but it seems it needs it to do damage at all, so my question is how much? My understanding is that Flama Magnitude reduces how much damage you need to trigger an ignite, So say Incinerate deals 1 million damage in the first few seconds, having 10% flammability would still trigger it right away no? while having like 100 damage and 10% might not have it reach an ignite at all to get through an enemy's ailment threshold?

I just don't have a clear measure or understanding of how much is necessary.

Bump