Right now DD is EBF and I have to attend a wedding without her when she's 4 weeks old (October 10th). I'll be gone about 5 hours. When should I start building a stash and when/how often do I pump to do it?

Right now she BF's every 2 to 2 1/2 hours. At night she cluster feeds from midnight to 3:30 am Chat Icon

This is all new to me because I exclusively pumped with DS and didn't have to balance BF'ing with pumping. Also, I had a lipase issue last time around and wasn't able to freeze milk. I lost over 300 oz because of it. I don't know if this issue is going to repeat itself. The LC told me it might not happen this time around. Not sure what to do...