Openings, Part 4 - The Pre-Count
The common way to count a song in is to just count 1 2 3 4 and away you go. If the bandstand is loud and you need to get the attention of the band, use a pre-count. The pre-count is 1 (skip a beat) 2 (skip a beat) and then proceed with your standard four count. The end result is 1 . 2 . 1 2 3 4.
The pre-count is also useful/needed when the tempo is very fast and 1 2 3 4 is too quick for all of the musicians to get ready to play (the drummer to sit up on their throne... bass and guitar players to turn their volumes up... harp player to get their harp to their lips, etc.).
Lastly, the pre-count is used when there's a pickup and not enough of the standard 1 2 3 4 count is left to give the band a solid feeling of where to come in.
A lick like the opening to "Juke" is an example of where a pre-count is not needed. You would count 1 2 3 and start on the "and" of 3 and away you go, only leaving out the 4th count.
An example of one that does require the pre-count is my "Here We Go" instrumental on the It Takes Three CD (http://amzn.to/29WkdQV). The pickup is four beats in total, allowing none of the standard 1 2 3 4 to be stated. In the studio for that song I stated 1 . 2 . and played my opening lick and the band continued the 1 2 3 4 in their heads and entered exactly on beat 1 of bar 1 of the 12 Bar Blues Form.
Special note...
When you play an exaggerated pickup like in "Here We Go," make sure to use a head-nod when the band is to come in (downbeat of Bar 1), this way you help to confirm what they think is the correct beat to come in on.