Bass sets a walking medium swing tempo and groove.
Drums and piano quickly fall into place with static-harmony.
Piano plays minimalistic but bluesy fills which set the tone for the song.
The rhythm section is using the intro to feel out whether to stay on one chord or play a I-vi-ii-V.
Near the 16th bar, piano plays a strong V bass note, and drums accentuate the downbeat to send a signal to begin the head. Cyrille picks up the cue and begins singing the head.
TIP: It is very common to count intros in a 4, 8, or 16 bar segment. The faster the tune, the more measures can conceivably be placed in the front of the head. Get used to thinking in 4 measure segments.
Tag and ending The last few bars tagged with an ending