The hotels in Sorong are cheap enough that there's no question it's just easier to book an extra day before. I did that last year at the Swiss Bel. I checked in at 9 a.m. while the lobby was full of divers waiting to check in later in the afternoon. The lobby is not air conditioned and the mosquitoes are fierce.
The breakfast buffet at the Swiss Bel is gross, with very unsanitary conditions. People put their hands in the food instead of using a serving utensil. The room is ultra tiny. The Muslim moaning of prayers is about every 4 hours all day long and it's very loud.
I'm staying at the Aston in February. It's got to be better than the Swiss Bel...I hope.