File as soon as your H‑1B petition is selected and received by USCIS—earlier filings lock in work authorization without gaps.

Submit the cap‑gap I‑20 request within 10 days of getting your H‑1B receipt so your DSO can update SEVIS before OPT ends.

If your OPT expires soon, ask for an automatic cap‑gap extension the moment your employer’s Form I‑797C arrives to avoid any payroll interruption.