When should I be worried?

Just be patient 🙂 It's very common after losing quick water weight at the start that your body 'recalibrates' its water weight level, causing a temporary stall on the scale (masking fat loss, which is still happening 'behind the scenes').
It's best to compare between similar relative points in your menstrual cycle to assess whether you're still making progress, 5 days is way too short a period to evaluate fat loss.

You should never be worried about it. It's a science fair experiment. Plan, analyze, assess, adjust.

Follow the same regimen for 4-6 weeks, then evaluate based on average weekly results over the whole time period. If you're female and of relevant age, compare body weight at the same point in at least 2 different monthly cycles to calculate average weekly loss rate.

From checking a TDEE calculator, I expect you to lose around half a kilo per week on an accurate 1500 calories (faster if male). . . but that won't happen evenly, it'll happen with many ups and downs (bumps on a gradual downhill slope). That's normal weight loss.

I'm female, your height, started losing at about 83kg and 59 y/o. I lost fine eating 1400-1600 plus all exercise calories. I admit I'm a mysteriously good li'l ol' calorie burner, and one person's loss rate sheds zero light on what someone else should expect, but I was almost twice your age, soooo. . . .

Hang in there. Odds are you're fine.

BTW, it's fine to weigh daily if it doesn't cause you emotional upheaval/distress. I've weighed myself daily for many years, starting well before even seriously trying to lose weight. It's just data, a momentary snapshot of my body's relationship with gravity. It's not a numeric score for my worth as a human being.

Best wishes!

Give it a month and if you still haven't lost weight then I would suggest to eat a little less.

Honestly I would worry less about weight at the beginning and more about sustainability and things like fitness and healthy eating. Two weeks in and your body is starting to get used to the changes you're making so it may take a while to see long term results.

If you want the maths it takes 7700 calories to lose 1kg so if you want to lose 0.5kg a week (steady and sustainable for your size) you need a net calories of -550/day. I'm 19, started at about 110kg with a BMR of about 1900cal/day so eating 1800 cal/day and burning about 6-700 cal through a mix of weightlifting and cardio like cycling, running and dance. Not overloading myself has made weightloss fun and sustainable as it's doable through small changes. If anything I'm able to push myself in my workouts with more energy and burn more and lose more weight.

Honestly my weight loss has slowed a bit through stress at work limiting my time at the gym and the water weight coming off but with what I'm doing being sustainable I'm feeling better, reaching fitness goals like being able to run for over 20 minutes comfortably at the end of a workout, being able to lift a new pb in weightlifting or being able to be more confident in my fitness and stamina. That imo is a lot better than losing 2kg a week and feeling terrible through overly restrictive eating and over exercising. Pace yourself and set goals that aren't just focused on weight and you'll see progress.

Hope that helps. Good luck