Short answer: coffee does not go dangerous, it goes dull. That is why it is easy to miss. Your beans do not grow mould, they just quietly stop tasting like anything.
Here is the timeline we work to.
The window that matters
Beans hit their stride about five days after roasting, once they have released some carbon dioxide, and hold it beautifully for around three to four weeks. After about six weeks the aromatics really start dropping away.
Ground coffee is a different story. It starts fading within minutes and is noticeably flat within a week.
Look for a roast date, not a best before
A best before date twelve months out tells you nothing. A roast date tells you everything. If a bag does not have one, assume it has been sitting a while.
How to store it
Airtight, dark, and room temperature. A container in the cupboard beats a clear jar on the bench, because light and heat are both working against you.
How to tell when it is past it
Two easy tests. First, smell the bag on opening. If it does not hit you, the coffee has gone quiet. Second, watch for the bloom when you pour hot water on fresh grounds. Fresh coffee puffs up and bubbles. Stale coffee just sits there.
Buy for how you actually drink
If you make one or two cups a day, a 250g bag is about three weeks of coffee, which is close to perfect. If there are a few of you, the 1kg makes more sense and works out cheaper per cup.
Either way it is the same Rise & Shine we pour in the cafe every morning. Come grab a bag and say hello!