For Reddit and HN, a few minutes. Please note that our working schedule is 14:00 – 20:00 UTC, therefore it’s best to synchronize your ops with it because upvoting threads early is more powerful.
For Reddit and HN, when we have to do the posts ourselves (including if they’re scheduled), there could be a +/- 45 minutes.
For Quora, we usually start working on the orders in less than 12 hours, and we provide a realistic number of actions per day, in order to not draw suspicion.
For Voat, Snapzu and TopTopic, we choose the best time for us. This should be fine for you as well, since for these networks we only sell upvotes and downvotes on posts done by us.