First wash both red and blue with color catchers. Then starch well before you start. Then mark. If you have already put the top together but not sandwiched be sure to stay stitch all around and then wash with color catchers.
I don’t normally prewash and had a red embroidery on a white background bleed really bad on my quilter. She washed several times with color catchers and you would never know that it had bled so bad. Good luck