Time to command is based on seniority, not fleet. I would plan on 10 years as things stand at present. If you want the 76 (or indeed the 75) then MAN is your only choice. The 75's are on the way out, with GLA moving to the A321 this winter. I'm not sure what is happening to the two 753's or how long the 767's will stay. The 767's fly for Condor during the winter and TCX pilots cover the flying.
There is talk of some training opportunities for F/O's. Quite a lot of the tech/CRM stuff is delivered over the winter and during ground transition courses by very capable and knowledgable F/O's. I'm not sure if there are any plans for F/O's to take up TRI roles, but I wouldn't be surprised to see it happening soon.