The coast is clear
Definition 1 of 1
Pro Tip 1/3Stealth Required
Used when secrecy or caution is needed, often when doing something unnoticed is crucial. 
She texted me 'the coast is clear' before I snuck out of the office early.
Pro Tip 2/3Opportunistic Settings
Indicates a good moment to act, because attention is elsewhere or less risk is present. 
He waited until the coast was clear to grab some extra desserts from the buffet.
Pro Tip 3/3Not Literal
Though it suggests a physical clearing, it's often used figuratively for any kind of obstacle. 
I'll apply for the job when the coast is clear and the company's hiring freeze ends.