Don't spray the copper if it is going to rain later in the day. It will simply be washed off.
If you already have anthracnose, spraying will not make the symptoms go away, but spraying would stop it from spreading. If the anthracnose symptoms are severe on a small plant, I would consider spraying it, otherwise I'd simply leave it alone. If your plant is mature enough to flower (and you expect it to), then you can spray on a weekly basis starting as soon as you see the terminal buds starting to swell.
If I was going to spray (and I don't normally), this would be the year to do so as we have had a warm, humid winter which increases the likelihood of anthracnose occurring.