If you do it Clock wise, Baie Comeau to Labrador, i would select a holiday or week end day has this section is the most dangerous portion. Big trucks are wide and dangerous, and the first section is tortuous with narrower rd and soft gravels.
The portion from Labrador to Blanc Sablon is almost straight, wide, flat and easy to do.
Week end of June 25th and July 1st are important holidays and should be ideal for 3 days ride usin friday as a holiday.
Have a safe ride.