你的句子没有问题。这样用的 now 可以分析为代词(许多英语词典也是这样认为的),也有的词典把 now is the time / moment / chance…作为固定搭配看等。又如:
Now is the best time to visit the gardens. 现在是最适合逛花园的时候。
Now is a propitious time to start a business. 现在正是开业的吉时。
Now is the perfect time to buy a new car. 现在是买辆新车的最佳时机。
Now is the moment to do or die! 现在是决一死战的时候了!
Now is not the time to discuss this. 现在不是讨论这个的时候。
Now is your chance to talk to him. 马上就是你和他谈话的机会了。