Check In Question for mixed class flight
 

Hi... I'm travelling with Emirates this week. My first flight to Dubai will be in economy class, my onward connecting flight will be in business class.

I understand that I need to check in for my flights at the economy counter as my first flight is in economy is this correct?
Will my bags be priority tagged considering my connecting flight is in business class?

Probably not automatically but if you ask perhaps. The check-in agent may comment on the fact you're in J on the 2nd leg and can certainly see it if they don't

They won't be tagged - however, the tag itself is irrelevant anyway. As you're booked into J on the second leg, your hold luggage should automatically be allocated and loaded into the "priority" bin.