As always, it varies by company, industry, and your business cycle. But in general, the best time to implement new ERP software is during slower periods of business (for instance if your business is seasonal, implement in the "off" season). You should also strive to implement a new ERP system when your business is fairly stable. Trying to implement ERP in the middle of significant organizational change will only disrupt operations further and you may end up not even finishing the implementation. See Also:Acumatica System Requirements