As most of the gold I've found is small, the biggest so far is the 3gr in my Avatar, I found an old pill bottle works well. (small one) You could use the old 35mm film canister, but they are normally a pop top.
I normally place the gold in the pill bottle, carefully pour just enough to cover the gold in to the pill bottle, screw top on.
When emptying the bottle, i do it in my ensuite sink, carefully pour the Alibrite out against the side of the sink, the gold generally stays at the bottom due to its weight.
Then run some water on a low setting into the bottle to dilute the small amount of Alibrite left. Pour out and re rinse several times and it's safe to handle.
Once I've rinsed enough, I get a couple of paper towel folded in half and turn the pill bottle upside down on to it and tap it to make sure all the gold is out. Then using your finger roll the gold to a drier part of the towel to dry it and the rest is up to you, lol.
As to how long, if the gold is reasonably bright and just covered with dirt, 24 hours is usually enough. If it's porous, you may need to get to the "dry" stage above and use an ultrasonic cleaner to shake out the dirt. However if it has ironstone or quartz embedded, then it can take a lot longer. How long, well that's the unknown, lol.
I bought a litre of Alibrite 5 years ago, I still have over half a litre left, you only need enough to cover the gold. Do it at the end of the trip........