Are you sure that this is a trans problem? The way you describe it makes me think you are talking about a running problem.
If you indeed have a trans problem I have to have a better description of juddering. Is it slipping, popping in and out of gear?
If it is either of the above I would try doing the same thing with the trans in first. That trans normally starts in second so by dropping into first you will be starting off in a different gear. It would be very unlikely to have a trans problem similar in two different gears. (unlikely but not impossible)
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician