Just a note from my personal experience that you might/might not find helpful. When I work two fronts (or sleeves, or pockets, or.....) I work them at the same time. I cast on with 2 balls of yarn or work from both ends of one. Then when I work a decrease on one side, say for the armhole, I work the matching decrease when I work the other side. If I have a decrease at the arm and neck on the same row, I will be able to do the matching set on the second piece and don't have to keep track of where I am and when did I do this way back on the first piece. Bonus: if I make a mistake and don't catch it until later I at least have matching mistakes and sometimes they don't really matter that much as long as the two pieces match. Here's hoping you or someone might find this helpful.