Best way to get priorclose from days previous to the previous

[scriabinop23]

I am having trouble figuring the best way to find the priorclose 2, 3+ days ago...

The closest I can get (no cigar, not accurate) is this:

int barsperday = 1440 / Bars.Period.Value;
closeratio = PriorDayOHLC().PriorClose[(i-1)*barsperday]/PriorDayOHLC().PriorClose[i*barsperday];

But obviously no contracts actually trade the entire 24 hrs (and thus have 1440 minutes of bars). So any idea how to get priordayohlc in *session* terms instead of *bar* terms?

Same goes for not running an indicator unless X days of data are present ? Instead of

 
if (CurrentBar < barsperday * period)
    return;

What is recommended?