King Air Pilot reported while descending to their airport taking evasive action to avoid a collision with an ERJ; Pilot landed safely at the airport.

Narrative

At approximately XA00 local on Day 0; I had just finished dropping a load of skydivers over ZZZ from 17500 MSL. I was on VFR flight following with ZZZ Approach on XXX.X. After dropping the skydivers; I immediately started descending and I turned direct ZZZ1 which is where we fuel the airplane. Once I crossed through 12000 MSL; I told ZZZ Approach that the skydivers and I were all below 12000 and that I was descending direct ZZZ1; this is the normal procedure at the operator I fly for. ZZZ Approach immediately approved my changing over to advisory frequency without issuing any sort of traffic advisories. Usually ZZZ Approach will alert me of all traffic from the surface to 17500 since I operate in essentially that whole altitude block and they will say something along the lines of 'no traffic between you and ZZZ1; frequency change approved' or they will actually give me traffic advisories for traffic in the area. As soon as ZZZ Approach approved my frequency change; I immediately started broadcasting on ZZZ1 CTAF to announce that I was setting up for a standard VFR pattern entry. When I got to about 8000 feet; I noticed a target on the ADS-B-in receiver in the airplane I was flying. The target was heading south towards ZZZ2 at about 7000 feet. I mistakenly assumed that I would be able to cross in front of the target since I assumed that it was a small piston single because it was in the practice area; at practice area altitude; and if it were a piston single; I would have been going close to 1000 kts faster than it which would have made crossing in front of it not an issue at all. I noticed that the target was descending and I decided to proceed direct ZZZ1 since I didn't think it would be a factor since I assumed it was going much slower. When I got to about 7000 MSL; I finally got the traffic in sight and I noticed that it was a ERJ about 300 feet below me so I immediately stopped descending and started climbing again. When I crossed over it; I saw it turn left to a northerly heading and initiate a very rapid climb.After considering this situation for the past few days; I have thought of a handful of factors that led to the near miss. First; ATC didn't issue me a traffic alert for the ERJ. I'm guessing this was because when I initially started my descent; the ERJ was not in my flight path and it was not obvious that it would be crossing through my flight path since the ERJ and I were both going relatively fast. Second; I didn't start looking at my ADS-B in receiver until about 10000MSL because I didn't think there was traffic in the area. I know that visual traffic scanning as well as scanning with ADS-B is of paramount importance and I let myself get distracted by listening to the AWOS and calculating how much fuel I would need to take on. I should have not been as absorbed by other tasks. Third; when I finally did see the traffic on my ADS-B receiver; I elected to continue straight ahead because of the assumption I made that the plane I was looking at was not a jet. I should have not assumed the airplane was a jet and I should have also done a 180 degree turn to pass behind the southbound aircraft. Even if the target were a piston single; this would have given me a much more comfortable distance from them. In the future; I will be much more conscientious of fast-moving targets and make an effort to give myself more space from all targets when possible. I will also encourage students of mine to do the same. I think the situation could have also been averted if ATC had given me a traffic advisory when I crossed through 12000 MSL because that would have prompted me to make traffic avoidance my first priority.