Patience ...

Home Depot probably got them packaged in a dark bag or box with no soil and they likely went dormant if not planted for a time.

You only just planted them and started watering them. Give them time to wake up from the 'trauma' of being up-rooted and stuffed in that bag or box.

Regards your other questions ... depending upon where you plant them, shade or direct sun, canna will grow quicker or slower. Sunny is best and it is recommended that they be in full sun to flower. Canna will live in shade, but may grow more slowly and refuse to flower. At least give them a partial shade environment if you are worried about too much very hot direct sun. Make sure your soil is not depleted by adding mulch if necessary.

Late June isn't the best time to buy rhizomes, but knowing how hardy Canna are, even so, they will likely still be viable. If they fail to start poking up shoots after about 5 or 6 weeks, take 'em back to Home Depot with your receipt and get a refund. Try again in early Spring.

Your question on the daffodils; those leaves are feeding your bulb for next year's blooms. If you cut them off, it is possible the bulb will not produce next year.

Happy Gardening,
Peggy