I personally would connect the two loops now. It is so much more easier before you attach everything with ballast or what ever you plan to use to hold the track down. Also if you put two crossovers facing opposite directions ( they do NOT need to be together) it makes running more trains and also doing real operations a lot more fun. You can move the inside to the outside and vice a versa. Remember in real life you do not see GIANT hands coming down to move trains. I try to keep the attitude that once it is on track I want to move it everywhere there is track without touching it again. But it is really about what ever YOU want. IT IS YOU AND YOUR DADS LAYOUT NOT OURS!