Bulgaria hasn't even joined the ERMII mechanism yet, and has to operate satisfactorily under that exchange rate mechanism for two years before being permitted to adopt the Euro as its national currency.
As Peter & Bulgarianfan have said, there's no chance of the Euro being used for many years - the last target which I read, in a speech by the Bulgarian Finance Minister, was a fairly wide one of 2010 to 2016, so don't hold your breath.
Baldur