1) From the git-go – с самого начала.
He didn't like me from the git-go, so I am not surprised that I am not invited to his birthday party.
2) Crank something up – начинать что-то или действовать более энергично, чем обычно.
He cranked up his pace not to be late for the meeting.
3) Swing into high gear/kick into high gear – «раскачиваться», работать все продуктивнее.
After he moved to a bigger city his career kicked into high gear.
4) Knuckle down (to something) – сосредоточиться и взяться за работу.
Please knuckle down to your studies! Otherwise you will have to learn everything at the night before the exam.
5) Let it roll! – синоним фразы “Let it start!” – «Поехали!».