Early May - it's time to getting geared up for the Es season. Bands most likely to be affected are 28/29MHz, 50, 70 and 144MHz. The lower bands generally start to show some activity in early May with 144MHz usually getting in on the act in early June.
It seems that lower sunspot years are generally good Es years. Let's see how that is borne out this year.
A good place to check on ten metre activity is Tony's 10 metre page