The majority of vesicles prepared from dispersions of phospholipids in water are nonequilibrium structures. Thermodynamically stable vesicles must display distinctive physicochemical properties. To investigate the size and stability properties of the vesicles formed in the catanionic mixture of single-tailed (SDS) and double-tailed (DDAD) surfactants, we evaluate the influence of the formation path on size, polydispersity, and equilibration time, by means of microscopy methods and water NMR self-diffusion. The different paths used involve mixing of solutions, mixing of solids, or dilution of preequilibrated concentrated samples. Water self-diffusion and microscopy show that all of the methods are able to yield vesicle solutions, but their size and polydispersity present some differences. Under the effect of a short sonication time, all solutions gain identical macroscopic appearance and with time they apparently equilibrate to a common state (as probed by water self-diffusion data). This stable state coincides with one of the previous formation paths - mixing of solutions.