So, where do I set first buy when I go to sleep in a couple of hours?
Think of the value.
If you value bitcoin more than other things, just buy now. If you would like to have more coins but don't mind having some other things as well, select a suitable buyback price.
My buying range is $300-$500 but obviously I haven't set the bids yet because it would look bullish on charts.
(I disregard sarcasm and seize the opportunity to teach )
The truth is that in the long run, any price right now is a good price to buy. Rpietela is probably buying really large quantities, thus he is holding out for a really nice price. But if you are buying just a couple coins, no sense in waiting. When they are worth thousands or tens of thousands each, you're not going to kick yourself for having missed out on scoring that extra $100 price difference that may or may not come. But you will kick yourself if the price skyrockets and you miss out not only on a lower price, but even the current price. Possibly to a really big difference.