The flush-out or testing will not affect installation of furniture and furnishings, as this can happen during or after the flush-out or testing, however, prior to beginning flush-out or testing, the following work should be completed to ensure that no toxins are reintroduced into your project space:

All interior finishes must be installed.
All punch-list items must be complete. 
All cleaning must be finalized.
Final testing and balancing of HVAC systems must be complete. Other commissioning tasks can occur during flush-out or testing only if they do not introduce any additional contaminants into the building.
Temporary filters and duct coverings used as part of the construction IAQ management plan must be removed.
Filters must be replaced with new filtration media, unless the system is configured to filter only outside air. If your project is pursuing EQc5: Indoor Chemical and Pollutant Source Control, these filters must be MERV 13 or higher.