"First move" refers to taking the initial action or making the initial decision in a situation. It is the first step towards achieving a goal or initiating a process. Full definition
A tenant, who had paid a security deposit when first moving in, experienced a residential issue and the landlord agreed to waive the early termination fee in writing. (law.stackexchange.com)
When cats first moved in with humans thousands of years ago it was because of their proficient hunting skills. (best-cat-art.com)
The images of the black paintings first move into focus, then out of focus. (brooklynrail.org)