It's different for everyone, you'll figure out you're flow. For me a 30ml bottle will last closer to a month. Just be sure to keep a supply on hand and don't cut it to close. Also you may want to consider if you're ordering from a vendor that mixes after the order is placed to go ahead and place the order wayyyyyyy early before you need it. I've found from my brief experience that many mixed to order juices taste MUCH better after they have had a chance to steep a while. Ordering them early before you need them gives a chance to let this happen.