Should I wait to have kids before Brazilian Butt Lift?

You don't need to wait for these procedures.  Assuming you are healthy you could be an ideal candidate for liposuction as you are young with good skin and localized areas of excess fat.
You already have a nice body, so the goal would be to refine your feminine curves by targeting the abdomen, hips / love handles, back, and medial thighs. The skin then retracts over the new shape to give the final result. If you want a little extra emphasis on your curves, you might also consider a Brazilian butt lift...

Liposuction is a very powerful technique in the right hands, and can have dramatic results in a variety of areas and a in a variety of patients.

That said, you definitely have to choose your surgeon correctly and make sure that he/she has the training and experience to meet your goals with absolute safety.
A key quality indicator is Board Certification by the American Board of Plastic Surgery. Don’t settle for less!

A
Brazilian butt-lift can certainly whether the changes that come with
childbearing. A tummy tuck is not a good investment if you are planning on having children shortly afterwards. From your pictures and your vital statistic's, you
seem like a good candidate to proceed with fat transfer to the buttocks at this
point. I would hold off on an abdominoplasty because you don't look like you
need it right now and you may want it after children.

Thanks for sharing your concerns with us. You can perform your procedures now without affection of having children later.To get a flat abdomen I suggest you waist and back Liposculpture, getting better curves especially in the waist, improving your body contour.Then, I suggested take the fat we get and transfer to the buttocks and hips, to mold them and get better volume, contour and butt projection, is that we know as "Brazilian Butt Lift" (BBL).Respectfully, Dr. Emmanuel Mallol Cotes.-

Hello dear!
Thanks for the question and provided information as well.
I suggest you wait until having children, because, during and after pregnancy, your body will experience multiple changes, and the results of a BBL might be compromised.
l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

A Brazilian butt lift combines liposuction of the
abdomen, waist, hips and back with a fat transfer to the buttocks to enhance
its size and shape. Although pregnancy may change your figure, it likely won’t
affect the results of a Brazilian butt lift. With pregnancy after a Brazilian
butt lift, you may carry some additional weight in your butt. However, your figure should remain proportional even as your weight
fluctuates. Fat that has been transferred to the buttocks will remain in that
region. Given that you’re planning to have children three or four years in the
future, investing in a Brazilian butt lift now will allow you time to enjoy an
enhanced shape before you take on motherhood.

 I think your timing is ideal.Pregnancy should not change the outcome of your Brazilian though it may stretch out your abdominal skin and cause abdominal muscle separation. Based on your pictures you're a great candidate for both liposuction and a Brazilian.After pregnancy you may not be a good candidate for liposuction depending on how your body responds to the pregnancy.