The first test for the MEV is for the Intelsat 901 satellite, which is running low on fuel. The Intelsat 901 satellite launched in June 2001 aboard an Ariane 4 rocket for a mission originally designed to last at least 13 years. The MEV is expected to extent the life by a further 5 years.
Then, and I quote (from https://spaceflightnow.com/2019/10/08/s ... or-launch/ ) :
After testing, The MEV’s fuel-efficient, xenon-fed ion thrusters will steer the Intelsat 901 satellite toward a new operating post at 27.5 degrees west longitude.
So it looks like Intelsat 901 will be moving to 27.5 West and taking over I907s operations sometime in Jan / Feb / March 2020, just as I907s expected life span comes to an end....will need to look at 901s footprints to see what type of beam SATBACK goes onto...assuming the MEV docks fine with I901, and the tests work, and can move it to 27.5w
Beams : I901 has two "spot beams"...along with a few "wide beams"...( https://www.satbeams.com/satellites?norad=26824 ) so if Satback moves onto those Spot beams, we shall have to wait and see what their reach is...