Take A Snapshot
My college professor used to make me take small snapshots of measures and then cover them up so that as I was playing the measure covered up, I was reading ahead to the next measure at the same time. This is great practice.
For example, you look at measure one and memorize quickly. Then cover it up with a piece of paper. While playing/singing measure one, you are making a mental note of measure two. Then cover up measure two and sing that measure while taking mental note of measure three. And so on………….
A sight readers, we are always looking ahead to see what the next bit of music is. This keeps us on our toes and prepared for what is coming next.