I’m afraid the goblins and undead spawn randomly, and right now, it is a pure random fn, instead of a weighted random fn. (On the TODO list. The very long TODO list.) It is possible, though unlikely, to never get invaded.
The goblin camp spawns at the same time as before (net worth 3500) but items are worth more now than they used to be (score system update) so it may feel sooner than before. Ideally, how long would you like before they appear?