In my complete tab of this song, I wrote the intro like this.

Intro
 G                  G       
-7---7-- 7---7---7--3----------3----------3----------3--------
--8---8---8---8-----3----------3----------3----------3--------
---7---7---7---7------0-0h2-0----0-0h2-0----0-0h2-0----0-0h2--
-----------------------------0----------0----------0----------
--------------------2----------2----------2----------2--------
--------------------3----------3----------3----------3--------

I've since realized that the notes are correct but may be played in a different way.
The B, G, D triplets are played as harmonics at the 12th fret instead of picked
at the 7th & 8th frets. The second part in the G chord is the same as before.

This allows plenty of time to let the last B harmonic ring while you slide down to
the G chord for the second half of the intro..

Intro (12th fret harmonics)
 G                          G       
----------------------------3----------3----------3----------3--------
--12---12---12---12---12----3----------3----------3----------3--------
---12---12---12---12---------0-0h2-0----0-0h2-0----0-0h2-0----0-0h2--
----12---12---12---12---------------0----------0----------0----------
----------------------------2----------2----------2----------2--------
----------------------------3----------3----------3----------3--------