Randy, with the spudding and drilling of the surface hole and setting surface casing, “operations” has begun. But just phase 1 (surface hole). There have been instances where operators have not followed up on surface hole drilling with a bigger rig to drill to TD - but this is rare for the most part.
As for the four well pad that you mention, normally the operator will drill all four shallow wells and case them with a smaller rig (spudder rig). Then move that unit off and bring in a big rig that is capable of drilling the lateral to TD. The time frame between releasing the small rig and getting the big rig will vary from days to months depending on the operator’s plans. But this approach does save the operator hundreds of thousands of dollars on a 4 well pad such as this.
Once big rig is on location, operator may drill all four locations back to back to back to back. Or only drill one or two so that they can frac and test the section before drilling the remaining wells on the pad.