If you’re ealy stage or a small business fast means now, minutes or days.
If you’re in a big corp fast means weeks and / or months. For real.
If you’re early stage and selling into BigCo and are told something is going to move fast set the appropriate expectations for your team internally otherwise your pipeline gets all jacked up and your manager will get frustrated with you.
No matter how enthuastic and excited the internal sponsor is they will run into the BigCo wall of friction and things will move at the pace they always move at.
Deals get done, they just get done more slowly. Knowing this will allow for better planning and less internal frustration.