reach (one's) stride
1. To start traveling or moving at a consistent, maintainable, and fast speed or pace. We started out the run slow but reached our stride as we came to the park.
2. To become proficient, comfortable, or confident doing something. Once you reach your stride at your new job, I'm sure your boss will be very impressed with you. It took me a while to get used to writing non-fiction, but I feel like I'm really reaching my stride now.
reach one's strideand hit one's stride
to do something at one's best level of ability. When I reach my stride, things will go faster, and I'll be more efficient. Now that I've hit my stride, I can work more efficiently.