Resting 30 seconds between rounds shouldn't be a problem, if you really need it. Since the goal of day 1 is to complete as many rounds as possible you should keep the rest to a minimum, only what you require to complete the next round.
Something I've found useful in balancing rest time with how hard to push myself (especially when tackling a new level) is to try and complete a round every minute. If I finish before the minute is up, then I get some rest time, or, if I don't finish in time I have to shorten my rest (or take none at all). This keeps me from being lazy and extending my rest times beyond what they should be.