To expand....
....in terms of day of week, the date for booking is two days earlier. For example, if you want to fly on a Saturday, the bookings will open on a Thursday. Also, it usually opens at midnight eastern. Therefore, a Saturday booking can actually be made midnight on a Wednesday night.
Based on the Africa experience, not all airlines let you hold the outbound until your return opens up. A way to try to get around this are to "hold" a return for the same day and then change the date.
