Is this a good exercise regime?

Long question ahead, sorry!! I’m a fifteen-year-old girl, going on sixteen. I’m five foot four, and I’m 9 stone, two pounds, or 128 pounds. My BMI is normal (22.0) and I’m a UK size 10, though I can sometimes fit into a size 8 both top and bottom. Is this really a healthy weight though, for someone my age/height? I want to tone up for a party that’s happening in three weeks for which I’ve bought a UK size 8 dress, so I’ve made an exercise regime, as well as cutting out snacks (I used to be a snackaholic). I do this last thing on a night, after I’ve eaten/drunk everything I need for the day. I take breaks when I feel tired. It usually takes an hour to do. This is based on exercises we do at school for aerobics; I don’t know all the official names of the different things, so sorry. D:

Stretches
March on spot (usually for 1–2 minutes)
100 toe bounces (where you bend your knees and kind of sway/stretch to the left/right)
100 bum kicks (kind of intense jogging where you kick your bum;D)
100 leg-ups (where you lay on the floor and kick your leg up)
100 knee-ups (where you bring your knee to your elbow)
100 star jumps
Arm bounces (for around 2–3 minutes)
100 sit-ups
Jogging (for around 2–4 minutes)
100 star jumps
100 leg-ups
100 arm bounces
100 knee-ups
Jogging (around 2–4 minutes)
100 bum kicks
100 star jumps
Jogging (2–4 minutes)
Stretches

But in your opinion, is this regime really effective? I seriously have no knowledge when it comes to sport/exercise, I just kind of made this regime up from total scratch. I’ve been doing this regime every day for a week now, and I’ve seen and felt a little bit of difference. I want to lose around 3 or 4 pounds, but mainly it’s just to tone up; weight doesn’t bother me that much. Will this regime help me tone up within 3 weeks?