new year goals, adjustments in training

okay so its after the december holiday and im ready to hit the gym again
but i got REALLLLLLLLLLLLLY lazy during the holiday and only gymmed 1 to 2 times a week so i gotta make a slow start again

first of all my goals in my training have been changed completly and obviously now a change in how i train has to come with it.

before i started gymming about a year and a couple of months ago ( i was extremly underweight and was laughed at in the gym when i first rocked up)
but i have managed to put on nearly 19kg since then, but my body fat% went up a bit too, not all of it was muslce (obviously, i was eating like a monster) , getting it to average around 12.8% when i was gymming which is too high, i want to get (more) ripped

in october last year i started kickboxing and QUICKLY learnt that gym fit is DEFINATELY not the same as been fit with regards to cardio, my fitness improved but still isnt where i want it to be

i want to start competing in kickboxing competitions and as such i want to put on some weight, while dropping body fat %, i want to get it too average between 9 and 11% through out this year, which i think is a reasonable goal. (with only over the counter suplements and no AAS, due to budget pretty much restricted to protein only)

BUT b4 i started kickboxing i had NO cardio in my workout, none. now im wondering where should i start on integrating cardio into my workout, such as say cardio only days, or after working out for size gains skipping and running on the treadmill ? kickboxing is twice a week for me atm for an hour and a half but i need additional cardio to improve my ability to go on for longer.

the other point tho, is that building is still my main priority and im wondering how my muscle gains will be comprimised if i add cardio (been on the same day as my normal work out, or cardio only days)

im 6ft3" tall and weigh about 90kg, if that affects how the workout would change in regards to cardio.

so in short, i want to get fit, while dropping body fat % ALL the while gaining weight still and was wondering what the ideal mix of cardio would be keeping in mind that my main priority is still muscle gains

You cannot loose fat, gain muscle, increase stamina and do kickboxing at the same time. You cannot be a BBer and a kickboxer...if you want to compete in kickboxing do a lot of olympic lifts, powerlifting and plyometrics and fight at you natural weight...which you are over now.