You can do this using ehsankia’s quote list CustomAPI - read more about it here.
What you do is click this link. It will generate three links and two tokens, a public token (8 characters long) and a private token (16 characters long). The public token is located within the first generated link. The private token is located within both the second and third generated links. The tokens are found after token= and before &data=$(querystring) Copy them and keep them somewhere safe!
What you want uses two commands: a command which uses $(count) and a command that tells how long ago the former command was used. I’m going to call the former command !test and the latter command !testtime
I’ve set up two such commands down below. Either copy and paste these commands as they are into your chat OR use the Nightbot dashboard to create the commands. Feel free to rename the commands as you wish. Replace PRIVATE_TOKEN with your private token and PUBLIC_TOKEN with your public token before adding the commands. Replace [!test command response here] with whatever command response you want (in your case it’s a response that uses $(count)).
IMPORTANT: It is safer to add the commands through the Nightbot dashboard. Add these commands through chat ONLY if you are sure no one else is in the chat, otherwise they might see your private token!
!addcom -cd=5 !test $(eval a=`$(urlfetch http://twitch.center/customapi/addquote?token=PRIVATE_TOKEN&data=$(time EST "MMM D Y HH:mm:ss z"))`;` `) [!test command response here]
!addcom -cd=5 !testtime The !test command was used $(countup $(urlfetch http://twitch.center/customapi/quote?token=PUBLIC_TOKEN&data=0&no_id=1)) ago.
Feel free to modify the command names or responses however you see fit. Just be sure to leave the $(eval) and $(countup) parts unchanged!