How long after a week of cocaine usage of about 2 grams is it safe to exercise?

I'd be concerned.: Regular use of cocaine can not only causes heart attacks, but also accelerates the development of heart disease in general (blockages in arteries of the heart). In that light, I'd be very concerned about seeing someone who uses cocaine exercise without getting a stress test first. Your inviting death.

It's safe: Arrhythmias are the major risk with cocaine abuse. I think the risk is highest for about an hour after use. Although prolonged lack of sleep might be an issue, I am not aware of any lingering risk for exercise. At your age the risks come from the cocaine use disorder, not from exercise. Ask for help there as well, you're worth it!