Usually its just before weekend or after weekend market will have a big move. When weekend its usually quieter, i think its because of many trader are stock player and follow the worktime.
i don't think so. Coz base on what i know anytime you want you can trade in the market as it is always open 24/7 but unless if you have enough knowledge and you know how to pick a good coin to trade coz that's the most important especially when it comes shorterm.. If you're a beginner and still don't have enough experience when it come shorting.. I suggest educate your self first coz its very risky and you need a lot efforts as well and that's base on my experienced.