On P1S which i have there are 2 prime lines located in front. First starts in Front Left Corner, goes to the right and then comes back - AND exactly after it finishes the prime lines it takes a 1-2 sec break with the nozzle 1-2 mm raised , just enough to start a blob 
Apart from the fact that those prime lines are a pain to remove sometimes, that small pause is enough to just leave a trace.
So i’d like to identify those prime lines and the pause after to just make 1 prime line and directly start printing.
BTW i do not see your startup code posted.
Cheers !