you are the only one who can figur out how to do it,
do it any way you feel it right, personally when the 3rd finger hits down i move the 1st on the next string,
the only (and its the best) advice you can have is to play with metronome always and play SLOW!!! too damn slow,
forget speed, try practise at 52 its the only way you will get focused and you will get rid of all the bad habits that dont allow you to play faster,
Remember practising doesnt mean playing as fast as you can,
practise is when you realize what you do wrong and correct it,
the only reason you dont play faster is because while you play you make mistakes, and to correct the mistakes you must play SLOWLY!!!!