I'm looking at building a new bench sometime soon so have be watching the bench and associated posts closely.
They look good size pieces of timber for a bench, but on the drying side I was always taught a year per 1", and I guess they are at least 2" probably 2 1/2". On that basis, quite a bit more drying would be advisable if that bench is going to stay flat. Also timber needs to have airflow to dry well, sitting indoors won't help it lose moisture quickly. Indoors could be useful at the end of the drying process to help it acclimatise to the dryer indoor conditions and lose the last few %. Well, that's how I understand it anyway.
Johnny B