As a project manager do you prefer involving the project team in building the time schedule or not? And why?

This is an odd question.  If you're trying to figure out how long a task will take, why would you not ask the opinion of the person who is going to do it? 

Yes,1st, keep in mind that a Project Manager is he who is a rider upon shoulders of team. developing confidence is basic part to get maximum efficiency and output. Getting Views from team as a Team leader is also "Sunnah".

Yes, PM should invite the  project team while preparing the time schedule for the project.  Getting the project teams and experts inputs are very crucial to get the most accurate schedule and estimates.

An important part in creating time schedule is to involve project team because project team will be ultimately responsible for completing all tasks and, therefore, it is necessary to get their feedback in almost all planning processes of a project.