Keep your lesson plans flexible! I know this is something we have to do in Real Life, too. It is even more important in SL because more unexpected things happen and there are often technical issues that cost time. In general, you have less control of the class and the environment than in RL.
However, this does not mean this is something negative or a disadvantage to RL classes. To the contrary, if you are flexible and keep your lessons flexible and if you are confident enough as a teacher and SL resident, the uncertainties can make the teaching and learning events in SL much more authentic and fun. The outcome might be different from what you had planned but as long as learning takes place and we keep relaxed about not having all the control, everything is just fine.
When planning flexibility into your lessons always keep in mind what your main aim(s) or objective(s) for this lesson are. So that when you have to leave out a stage it is not one that was important for the main objective(s). If you don’t think in advance about what you could leave out, shorten or change, what often happens it that there is no time left for the last stages, which might be more important than some of the previous ones.