The best metric is progress -- and the easiest metric to measure is increased weight on your lifts. Especially beginners, you'll probably be able to add 2.5, 5 or even 10 pounds to your lifts ever week or two. At that rate, it doesn't take too many weeks before you have some nice increases. "Big gains" are a fallacy. It never happens that you just role out of bed one day and add 50 pounds to a lift. Instead, it is a slow progression.
With that said, there are also many variables.
Are you "young" or "old"?
Have you ever trained before?
Do you have your diet in order, eating enough protein?
Are you too fat (and need to lose weight), or are you lean?
What is your goal? (strength, endurance, look good, compete, lose weight, gain weight?)
What is your rest time between sets? (30 seconds or 3 minutes)?
It is a popular opinion that beginners do best with 1) multiple movements per workout, and 2) compound movements (squat, bench, deadlift, chinups).
Starting out, you won't be able to do much weight on these, so it is conceivable that you could do all 4 exercises, every workout -- with rest days. But as you progress, and add weight, and sets, you won't be able to do all exercises every workout. You'll start to notice that whatever you do first that day, is your best lift, and what you are doing last -- is your worst lift. Doing squats first, you'll set a personal record. Doing bench last, you'll be lucky to do the same weight you did last time. At this point, you will need to start breaking movements up into different days (upper body one day, and lower body another day is common).
30 minutes per workout -- sure. If you are focused and efficient. You do these 4 exercises for 6 months, add weight when you can, at 30 minutes per workout -- then you will be significantly stronger in 6 months. I also bet you will want to spend more than 30 minutes per workout after 6 months.
Oh, and please don't waste your time doing doing curls. You can add curls after you can do 3 sets of at least 8 reps, bodyweight chinups.