What type of walking do you do? treadmill? outside?
IMO, Usually you want to start off slow especially if you are just starting to get back into doing cardio and then slowly increase the intensity. Now that I'm doing cardio, i stick to walking on a treadmill at an incline and i either increase the speed or incline to increase the intensity of the work. That's just what i've been doin now for my cutting. Oh yea, and i do 5-7 days a week of 30 minutes might be increasing it soon.
Also to what is better between HIIT or Low intensity? fasted cardio or not? you are going to come across alot of different views on this because it's an on going debate over whats better. What i found worked for me is doidng low intensity fasted cardio first thing in the morning or low intensity cardio post-workout. I'm sure everyone else does things differently.