T1ρ-Mapping requires acquisition with multiple Spin-Lock Times (TSLs) in order to fit the free parameters of the model. Reducing the #TSLs poses a trade-off between acquisition time and estimation error. Also, the choice of TSLs has a significant influence on the fitting results. A previous study analyzed the Cramér-Rao Lower Bound (CRLB) as an optimization criterium for the TSL choices using different #TSLs for Mono-Exponential models. This study extends the use of CRLB for Stretched- and Bi-exponential models using complex-valued fitting via Non-linear Least Squares. Experiments show that optimized TSL sequences improve parameter estimation when compared to non-optimized TSL sequences.