There will be no life to start with, just a climate hospitable for life.  It will take Slough's emergence and presence on a planet to get life started.  Whatever things Vestec has created to move within the depths of space cannot be classified as true life, instead being autonomous, physical pockets of chaos.

It makes me really think of Bayonetta, actually.  In that game series, the angels are vile and twisted eldritch creatures in shells of flawless gold and marble, in essence things purely organic but still not proper life.  Demons, meanwhile, are vile and twisted creature-like machines of diabolic, hateful metal.  'Life' created by Toun or Vestec, for instance, without Slough's help, will probably take extreme forms such as these.

The kind of natural life that will colonize and thrive on planets will come ultimately from Slough, though other gods can disseminate it once it exists, which it will after the Big Bang has created a universe hospitable for it.

That's not to say that once the world exists and Slough's power has touched the planet, gods can't create life on their own, but until then (or afterward but independent of Slough's presence on a planet) gods cannot create real life.