please check, if the hCD2-cre mouse serves your purpose. I have attached a publication for cre mediated deletion kinetics comparing hCD2-, Lck- and CD4-cre mice in the thymus. Please check:
Article Activation Kinetics and Off-Target Effects of Thymus-Initiat...
The mouse strain in question you will find here: https://www.jax.org/strain/027406
And our comparison of Lck-cre and CD4-cre mediated deletion in thymus and peripheral T cells, respectively, you will find here:
Article A role for the histone H2A deubiquitinase MYSM1 in maintenan...
A reviewer of my results suggested hCD2-cre mice to investigate T cell specific deletion at the earliest stages in thymic development, so I hope that helps.