Storing sap

Hi all, I have a quick question about storing collected sap before boiling. The resources I've been reading say that you can keep collected sap stored under 3°c and use within 7 days. My question is, can you keep adding sap to the same collection pail from different days? And if so, I'm assuming that the 7 days would be from the first day you added sap? Just want to confirm!