It's never too late. One of the mums in my Baby Buddies group has recently re-lactated (I think she started at about 3 or 4 mths!)
If you are not wanting to be getting into the habit of expressing then I probably wouldn't start. I would probably only express if it was really uncomfortable. Like Flowerchild said with supply and demand. The more you express the more you will produce.
But no it's not too late
Good luck