This is actually the approach that Gina Ford advocates in her Contented Little Baby Book. If you want a step by step instruction manual for how to go about it, I suggest you have a look. Don't worry about the routine if that's not what you want to do...but her guidelines for expressing at certain times of the day in order to have the full expressed feed ready to go for evenings are good.

Mind you...I tried it and I found that my body simply did not respond to the pump. I had a great deal of difficulty expressing and so I have this virtually brand new electric pump in the cupboard collecting dust. I tried expressing again this time around with DD and same thing. I just can't express.