Last year’s zakat must be paid immediately once it is due. You can’t give
it in installments.
However, you can estimate next year’s zakat and give it on monthly basis
and once the date is due, you calculate how much you gave and if there is a
balance left, give it on the spot.

I have couple family members whom I give zakah money every month. I pay let’s say my 2.5 % of wealth will be $6,000 I pay according to that and I can’t wait till end of the year to give them zakat money because they need money every month to survive so is it ok for me to give them money every month instead of waiting till end of year because they need it.