After the enterprise is genuinely established and operating, since a business that has not begun is not a real operating enterprise. That usually means premises, equipment, licences, insurance and at least the beginning of actual work.
The application follows the business, not the intention
Hypothetical example: the partners incorporate, open a bank account and apply immediately, presenting a plan. That file describes an intention. Build the enterprise first: secure the yard, buy the equipment, obtain licensing and bonding, arrange insurance, hire the first crew and take on work.
Keep the paperwork as each step happens. Then apply, allowing for the responsible agency's current published processing times. In the meantime, neither investor may work in the American business without a status permitting it, which means the establishment work has to be structured with that in mind and may need the U.S.
partner or hired staff to carry out. That constraint is uncomfortable and it is real, and planning for it is better than discovering it after a yard lease is signed.