Our new Welsh had a long thick forelock I clipped a bridle path and went just up on the bone. From behind his ear I cut one clipper width along the base of each ear toward his forehead. Forelock hair came off in handfuls. That narrowed it considerably. I then removed the fuzzy stuff underneath and clipped the growth pattern on the forehead into a V (gotta be careful here). To trim the length I'll twist it around pulling downward as I do, two or three times then remove maybe an inch then comb out to see how if falls. If a few snips have to be done hold the scissors vertically to avoid the chopped look.
Can you post some pics. I'm trying to picture it in my head but having a tough time. Thanks :)