is march/ april a good time to visit ?

Sayeda, I think you may visit these three places in April. I went to Beijing in mid March of 2011. It was still cold. I remember that I still wore winter clothes. The temperature will rise in April. The temperatures in Guangzhou and Shenzhen will be higher.

Lucy, thank you very much. I'd request for a further information. do i need to prebook all the hotel/accommodation options? my route plan is Beijing- Guangzhou- Shenzhen. is it ok if i book my hotel at Beijing only and then do instant check in at Guangzhou and Shenzhen after reaching there?

Sayeda, it isn't the peak time when you come. But I personally suggest you prebook your accommodation in advance. That's how I take a trip. I prefer to make everything settled before my trip starts.

It doesn't matter if you change your itinerary because most hotels allow you to cancel your booking freely.

Lucy, thanks a lot :)