Now, while more than a year of L-1A remains. L-1 tolerates immigrant intent, so she continues working and extending L-1A while the I-140 and later the I-485 are pending; the goal is to adjust before the seven-year cap.
Start the immigrant clock before the nonimmigrant clock runs out
L-1A carries dual intent, so filing an immigrant petition does not jeopardize extensions or entries. The realistic sequence is to file the I-140 for a multinational manager promptly, with premium processing if available, then file the I-485 as soon as a visa number is available for her category and country of chargeability, and meanwhile extend L-1A up to the cap using recaptured days to add margin. Once the I-485 is pending she may obtain employment and travel documents, but continuing to hold L-1A while it is pending is usually preferable, since it lets her travel and work without those documents.
If the cap arrives before adjustment, she must leave the United States and remain abroad for a year before a new L-1 or H-1B, though the immigrant process can continue by consular processing. The son’s age drives the timing as much as the cap does: his derivative eligibility depends on being under 21, adjusted for the petition’s pendency, when the family seeks to adjust. The Canadian roastery must remain in business throughout, because the immigrant category, like L-1A, requires the qualifying relationship at filing.