Pumping schedule

I need some advice on creating a pumping schedule. I’m returning to work sooner than expected (finances, family issues, illness). My job is very accommodating for nursing mothers, but I have less than two weeks to get a stash built up for sitters.

Babe is 4.5 weeks old. LO nurses roughly every 30-90 minutes. It’s near impossible for me to get them to nurse greater than that. Nursing sessions are like 40 minutes long. LO sleeps for 4-5 hour stretches. How will I ever create a solid stash for short feeding sessions?? I tried extracting some milk after a feed, and I got about an ounce. Thanks