Forward to web proxy script

Hi all, i have a hotspot users and i’m allowing them to login in specific time.
Now, i need a way that when a user attempt to login on a wrong time, a web proxy page shown telling him that is a wrong time. Or may be another way no need for web proxy.
Thanks in advance

ftp to your router, edit webproxy/error.html (Make this page say what need to be said)

Then use this guide
http://wiki.mikrotik.com/wiki/How_to_Block_Websites_%26_Stop_Downloading_Using_Proxy

I have not messed with restricting access by time, but all that info should get you 90% of what you need.