A bite at/of the cherry
Definition 1 of 1
Pro Tip 1/3Opportunity Context
Used when someone gets a chance to do something usually done by others. 
With the manager away, I had a bite at the cherry to lead the project.
Pro Tip 2/3Not Recurring
Implies an opportunity that might not come around often. 
This job opening is a rare bite at the cherry, and I should apply now.
Pro Tip 3/3Positive Connotation
Generally used to talk about positive chances or desirable opportunities. 
I never imagined I'd get a bite at the cherry to study abroad.