There are at least two ways to treat a first postdoc or the first year of any academic job post degree.
The first is to use it to work over the backlog of problems that you saved in your "work backlog" notebook. You have one of those, right? If you are still as student, reading this, I suggest you get started on one immediately. If you saved descriptions of work that you had to put on hold during your dissertation work along with hints, and if you reviewed and updated the backlog periodically, you can probably get quite a few publications started or even into the pipeline by the end of your first year. You don't really want to be starting with a clean slate.
The second way to approach the first year is to get yourself attached to other researchers in your field for collaborative work. If the institution has a large enough faculty, most of them can be local. You may not be "first author" on everything (anything), but you can get out there, but also establish relationships that will last and boost your productivity. If you are in a small place, or isolated by subfield, you can, perhaps, use conferences to meet people and try to set up communities of interest, or join those that already exist.
In general, though, it is good to be working on a variety of things of different difficulty. Some of them might result in early publications, but aren't earth shattering. Others, you can work on for wider impact, though the going may be much slower.
And when you go for the next job, that backlog of work in progress is your friend.