
An absolutely essential element in blues guitar is the turnaround. It is a basic function of blues music that the turnaround happens at the end of the progression and flips it over back to the beginning of the form.
When playing a standard 12-bar blues, the turnaround occurs in the last two bars, 11 and 12, as the tonic chord (rooted in the key you’re in) moves to the V (five chord), which then resolves back to the tonic in bar 1 of the next 12-bar chorus.