Teratomas are not the very common testicular type of tumours and could spread. However, before the operation is done, a clinical and paraclinical appraisal is usually done , to determine whether the tumour has already attained other structures or not. This usually helps your surgeon to decide on the appropriate treatment option after surgery, and the speed of installation of this treatment. I believe your surgeon must have done this before surgery, and the speed and invasiveness, type of treatment to be taken are usually based on these findings.
However, I would advise you to get to take your chemotherapy
as soon as possible, for testicular tumours at times spread very fast, and during the spread period, are clinically silent with no signs and symptoms, revealing themselves only in an advanced stage.
Hope this helps,