What is the evidence for the 30 minute mark? This workout alternates strength moves with a few minutes of cardio. And a lot of the cardio moves build muscles as well. We do burpees, jump squats, things like that. Why should you do the strength exercises first?
Well, you're a woman so if you want, you don't have to do strength exercises.
When you workout properly for 30min, that means doing cardio workouts too, you will trigger the afterburn effect which is just a fancy way of saying you're going to burn more calories than you would otherwise because your body will require more energy through the day.
It's like when you're doing calories counting when you're eating. Women do this a lot. Say a cupcake has 80calories. Well you can calculate how many calories you burn if you do X amount of exercises and if you do 30-35min of proper training, with a focus on cardio, you will double that calorie burn. This means that if you do a workout that burns 300calories (this is an ok estimate) you'll actually burn 300 more through the day... after you finish the training... the afterburn effect.
You can trigger the afterburn effect even with the tabata workout for instance if you do it properly, but it's really, really intensive.
Insanity, tabata, t-25 such things are usually not a good idea if you're not ready to go the full package. going halfsies is going to do more harm than good. For instance, I messed up because I overdid tabata when I first started out and because I didn't know about the 6-10min warm-up. By messed up I mean I did 2weeks of workout... and then took 2-3weeks off because I overdid my workout so I started performing mroe and more poorly. Muscle fatique.
Why strength first? Proper cardio is exhausting and will decrease your ability to do proper muscle-building training. But doing strength training first and then cardio you will enhance your strength training because of the increase in bloodflow and adrenaline. But as I said, you're a woman.. so strength training for women is different than it is for men, and the goals are different too.
My suggestion, find a comfortable workout that you can do for 30-35min every 2 days. Preferably, it should work your whole body. Keep your pauses between sets short, 30s-1min, do every routine at least 3 times (so 3 sets of 10 burpees for instance) but you don't need to do them one after the other.
So for instance.
do 10 burpees / 40s break
then 20 jump squats /40s break
20 mountain climbing with each leg / 40s break
15 jumping back and forth / 40s break
And then take this whole routine and repeat it. 10 burpees / 20jump squats / 20 mc / 15 jumpings and then again. three times.
Then find another 4 exercises you can do and chain them all up nicely.