Using Servos in Sync with Printhead Movements

I'd like to move the printhead to a specific "cleaning" location behind the stage of my custom printhead, then activate a servo that will clean the needle tip of my paste extruder. I want to make a custom M-code that will do this. I'm using Marlin on Ramps 1.4.

If I use plan_buffer_line to move the printhead to the cleaning location, then use the servo.write command, will Marlin wait for the move command to finish before activating the servo? If not, then could I use st_synchronize() after plan_buffer_line, but before the servo command in order to make sure the servo only moves after the printhead has moved to the desired location?

At the end of a print, why not just retract some filament back into the extruder, then move the extruder off of the print area, bring it down to 0 and then have it move across on the print bed, thereby scraping the nozzle clean?

If it's at the beginning or end of the print, then simply put the GCode in the beginning/end GCode in your slicer. Easy enough to move and use the servo without anything special.

madmike8, I'd like to be able to initiate the cleaning at any point during the print.

rcjoseb, that will work for the plastic extruder, but I'm using a pressure-based paste extruder (no retraction). The paste gets stuck on the sides of the needle tip sometimes and causes smearing issues.

Ideally I could just types something like M9999 and hit enter, rather than type a whole bunch of Gcode. What I could do is write the gcode out before hand, then copy and paste it into pronterface whenever I need it. But I don't think I can copy and paste multiple commands into pronterface.

Secondly, I'm not sure if the servo command will be executed instantly, or if it will wait to be executed until its turn in the buffer. For activated a pin using M42, it executes quickly instead of waiting for the codes in the buffer to execute, so I was thinking that maybe the servo will behave similarly.