How do you pump while EBF?


My baby is 1 month tomorrow, is EBF & I love it, no problems there! I’m curious how to start pumping so I can stash some milk for when I go back to work. I’m a high school teacher & I go back Feb 19 and I’m wanting to have plenty of milk frozen for her so that she can still get my breast milk while I’m gone. When I’m home with her she’ll get the breast. I’m just not sure when to pump or how frequently. I don’t wanna store a bunch of 1oz bags... so not too sure what to do. Any tips y’all have would be great!