Why after just replacing my TC would it jump time as soon as the gear changed?

are you sure the tensioner for chain was put on correctly

agree with goodguy

Aside from the timing chain tensioner, are you sure that the balance shafts and chain were installed correctly and timed correctly? Did the camshaft or crankshaft position sensors(s) get broken by chance? Tear down and re-inspect and line everything back up again. Pray you didn't do internal damage if anything is off.