You can eat the blueberries if you want too without washing them first however it's advisable and recommended to wash the blueberries and any other fruits before eating them to get rid of any pesticides or bacteria that may be on the blueberries or other fruits.
I've eaten blueberries before as a kid from a farm without washing them first and have never gotten sick but if you do buy blueberries then those blueberries likely have traces of pesticides that the farmers use on them so wash those blueberries first before eating them first.
But if you do wash the blueberries wait until you're ready to eat the blueberries first before washing them as washing them and then freezing them can make the blueberries skin tough.
To wash blueberries place the blueberries in a colander and then dip them in cold water and swish it around.