There are two way you can do this.
1. Have the same form and change stuff come 6.00
2. Have two forms, and load them depending on what time it is.
The second is probably the easiest. When you load you application have a splash screen/form which basically displays the logo and welcome message. In the code behind this form have an IF statement to check the time. IF the time is >= 6.00 then load the appropriate form, ELSE load default form