if you use AMOS I would suggest the book by Collier (2020), especially Chapter 6&7
Book Applied Structural Equation Modeling Using AMOS: Basic to Ad...
For examples of how to do longitudinal mediation analysis with SEMs you can also check my publication, where I demonstrated the application of a synchronous and cross-lagged-model for mediation using SEM.
Article Does social support mediate the effect of multimorbidity on ...
As further reading, if you are interested in longitudinal modelling with SEM in general, I would recommend having a look into: