The years you have to wait to get a felony expunged depends on the class of the Felony.
For class 4 felonies and if it's a first offense then usually within 3 years the Felony can be expunged from your record.
Any felonies that go above class 4 felonies you have to wait at least 5 years before requesting or getting the Felony expunged and if the Felony is your second or more offense then you may have to wait up to 10 years in some States to get the Felony expunged.