Great you're starting your treatment AspiringMD.
It may be hard to floss between your teeth at this stage, due to the brackets and wires getting in the road. What type of floss are you using? I use oral b super floss, due to it having a stiffened end, then a spongy area, then normal floss. The stiffened end is tiny and allows me to gently thread it between my teeth at the gum line, then floss as usual. If the area were tender, or too 'tight' to thread through, it's best to thread the stiffened end up from below the wire for the lowers and from the top down for the uppers.
I found that flossing during the first week with braces was slow, but I quickly got back to flossing within three minutes. Practise seems to be what works best and flossing once a day is essential for the health of your gums.
Great that you don't have any soreness!

I've not had soreness and my treatment has gone 2.5 years so far. I've not had an expander, but if you have any issues talking with it, please let me know, as I have a great 'passage' that you can practise, that will help you find talking easier.
Good luck!