Rule number one of a TTT is that the speed doesn’t change.
If someone is stronger they pull for longer, if someone is weaker they do a shorter turn.
Don’t have it so the strong guy goes to the front and pulls really fast for a minute and then the weaker guy slows the whole thing down for a minute. This will result in the weaker guy being crucified when he should be resting, as he will be going hard on the front and then will likely have to go just as hard on the wheel, and most likely do a full sprint to get on the back of the line.
The stronger guy on the other hand, will have more recovery and will therefore likely push the pace even more making for a nasty feedback loop.
Figure out roughly how fast you want to ride and don’t let the speed change. Also bear in mind that uphills everyone has to go harder relative to one another so it might be a good idea for the weaker rider to pull up a hill. The stronger guy should pull down it as everyone will get more rest relative to him.