I started at 29 and finished just short of my 35th birthday so 4 in under 6 years. The gaps were 18 months, 2 1/2 years (with a mc inbetween) and 22 months.
It was hectic, we have no family support so just DH and me, DH is great I couldn’t have had 4 DC with a man who wasn’t prepared to do 50% of the work. Mine were all good sleepers, all BF and coslept for at least the first year which meant I slept. What else? Oh it wrecked my body, my pelvis is still recovering 9 years later but that could be me. You will never be rich they cost a fortune, I was a SAHM for 12 years as childcare for 4 is too expensive, you always need a 7 seater and a big house. Holidays cost a bomb too, we take up a row on a plane and 2 hotel rooms.
Nothing in life is guaranteed though, start with your first and see how you go from there, best of luck