Mark a scale with a ruler on each page of your pattern, Or a box that must measure the same on each page.
That way when you do get a chance to scan your images and place them on a page you can adjust the image until the box or scale is exactly right. It's tricky but that's what I did.

That's a great tip. When I work with hand-drawn patterns, I take a photo of it with my camera, trace the pattern onto a new image layer in my photo-editing softtware, and then print at various different dimensions. A bit of trial and error usually gets it right. But your idea of using a ruler would make things so much easier; I wonder why I've never thought of that before.

hee, hee, I know! I fussed and fussed with my pattern before I had my ah ha moment!