gradually lower your caloires. not all 500 at once. 200 each time when needed until in a 500 calorie deficiet ... thats if you choose to go that way and just follow a calorie reduce diet. carb cycling is a bit different. check the stickies. and yes you could start this right away.
Id reccomend starting with only 2days of HIIT at first. let diet do its jobs and add cardio when needed.