Week 6, or so it seems.
Think of what you did last week, 5x 5 min cruise on 30 second recovery, and get rid of the recovery. 25 minutes at tempo pace. Don't go out too hard, you need to finish strong. The last 5 minutes will sting a bit, and it'll be your job to hold the effort toward a solid, evenly paced tempo run.
How 'bout we go 15 minutes before the turn around? This ensures you have an extra 5+ for cool down so you're not too sore the next morning.
See you there!