Emphasizing urgency:
* No time to waste, act now!
* Time is of the essence, don't delay.
* Seize the day, there's no time to waste.
Highlighting opportunity:
* No time to waste, make your mark.
* Don't let this chance slip away, no time to waste.
* Opportunities are fleeting, no time to waste.
Motivational:
* No time to waste, let's get this done.
* Let's make every moment count, no time to waste.
* Time is precious, don't waste it.
Contextual:
* [Product/Service] - No time to waste, get it now!
* [Event/Campaign] - No time to waste, join us!
The best slogan for you will depend on the specific context and message you want to convey.