The correct action is:
- Do hit reply straight away upon receiving it,
You want to (a) maintain top of mind and (b) positively identify that you are on top of things and a fast actor
- Simply type "Fantastic, hear from you then. Cheers, John"
Nothing else. Hit send.
- Of course, vary the formality per your situation and personality. So maybe "Fantastic, that would be great, John" or "Thank you, looking forward to it, John Smith" or whatever the case may be.
I use it as a chance to push my phone number
- "Thanks, I'm here any time - Johnnie 255-1236969"
I always recommend:
"A little enthusiasm never hurt anyone..."
Within your personality style, it's ok to show a few words of enthusiasm. For contracting and specific projects it's great to mention the project and show you're all over it, in one or two words.
Your next question may well be, if you don't hear back quickly, what to do next?
Yes, after "some days" it's cool to again just reply to the email in the shortest manner; basically the identical email again: "Thanks again, here any time, John 255-1236969".
You are in the most delicate and decisive part of the negotiations now!
You have to
but of course
Enjoy!