Copper is typically sprayed twice a year once in late fall after leaf drop on a nice warm day and once in spring before things start growing. I would recommend wearing gloves and a mask when applying fungicides and pesticides. Fungicides such as captan are hard on the eyes and work great on preventing black rot. Not all grapes respond well to certain sprays so you might read this prior to spraying anything http://homeguides.sfgate.com/spraying-fungicide-grapevines-48449.html. Sometimes people want to use sulphur as a fungicide as opposed to immunox or captan and it’s good to know how that affects grapes. The organic approach is slightly different than the chemical approach so before we go a lot further which one will you be using? In Kansas I use chemical fungicides and pesticides primarily. Some people use methods very different from what I do in this high pressure area. You might enjoy some older posts on the subject eg.
Dormant Spray and Copper Spray
There are many other posts if you type spray in the search section by the magnifying glass at the top of the screen. Believe me what your after is in there. I think the simplest advice I can give is most sprays require application every 7-14 days depending on the sprays. It’s best to use more than one type which prevents pests from building up an immunity. I would highly recommend you read through Scott’s low impact spray schedule
Low Impact Spray Schedule (old version)