Yes you are correct:
There are 3 pads on the Top
and 2 Pads on the bottom.
The suggested pin numbers/names would be:
1 1 ->Top middle pad (signal)
2 MNT_1 ->Top left mounting pad
3 MNT_2 ->Top right mounting pad
4 MNT_3 ->Bottom left mounting pad
5 MNT_4 ->Bottom right mounting pad
As explained in the Style guide on the Pin Number Section
Look at this post on a similar part, for footprint hints.