An endoprosthesis delivery system includes an expandable endoprosthesis including a side branch portal, a first primary sleeve releasably constraining a proximal portion of the expandable endoprosthesis to a collapsed configuration, a second primary sleeve in parallel with the first primary sleeve, the second primary sleeve releasably constraining a distal portion of the expandable endoprosthesis to the collapsed configuration, and a secondary sleeve within the first primary sleeve. Upon release of the first primary sleeve, the secondary sleeve releasably constrains the proximal portion of the expandable endoprosthesis to a partially expanded configuration allowing access to the side branch portal via the partially expanded proximal portion of the expandable endoprosthesis.