Every 2.4 hours. Your problem at this moment is as you are at 30% voting power it'll take you 82 hours to get to 100%.
At 100% voting power your vote worths 0.001 sp (at this moment because your sp s 15). That converted to $ at this moment means 0.0025$.
At 30% voting power your vote worths 0.0003 sp. That converted to $ at this moment means 0.00075$
So you waste the same voting power(2.4 hours) but means significantly less.
I think it's very strange nobody helps you before me...