File early enough that a decision, including any request for evidence, arrives before the ground thaws. Trail construction has a fixed window between spring runoff and freeze-up, and a late approval costs a full season.
The build window sets the filing date
Trail work in northern Vermont runs roughly from the end of mud season to the first hard frost, and a state-park contract will have completion milestones tied to that window. The petition should therefore be filed in winter, with the specification exhibits, training records and the affiliate's contract review completed before the holidays. Premium processing shortens the initial decision but does not shorten a request for evidence, so the file has to anticipate the usual questions about what makes the knowledge company-specific and who controls the work on site.
Confirm the senior builder's continuous year on the intended filing date, because a seasonal layoff in the previous year may push the eligible date later than expected. If the affiliate's contract is still being negotiated, wait for signed terms rather than filing on a draft; a change in the control language after filing can undermine the case. Once approved, the builder should not begin work on the trail before his admission in L-1B status.