I did this tour a few years ago and it was amazing, you will have a wonderful time.
Be prepared for some early starts and you will be on the go the whole time but it is worth it. I went in November and the temperature was lovely but would advise you take a light cardi or fleece for the early starts and some evenings it got a bit cooler. Also plenty of wet wipes or antibac spray and if you are prone to a dodgy tummy take some medication. A few people on our trip suffered with a funny tummy (myself included) but it didn't last long and certainly didn't spoil the experience. Highlights for me were Ranthambore where we saw a beautiful tiger twice, of course, the Taj Mahal and also Varanisi which was very special, do go to the evening ceremony if you can, I found it very moving.
I hope you have a brilliant holiday.