Diego, no question is too amateurish!, well except is Nikon or Canon better!(posted 9180 days ago)Firstly, you can get the colour head settings for filter grade from the Ilford web site or from the info sheet that came with the filters. You may not still have this so go and have a look at the site, you can get all the info in PDF format.
I have only used FP4 and Ilfosol in 35mm format but have found for my camera/developing technique/enlarger I need more time than the quoted figures to get negs that consistantly print at grade 3 on MG. I use the filters as I find it easier to drop the next one in rather than setting new values on the colour head. For the record, I rate FP4 at 80asa, develop it in Ilfosol at 1:9, temp of 20C, for 6mins.