when to put my baby seedlings in a bigger pot

[orchiddream]

.I received a flask of seedlings a few months ago. I bought my own shot plastic glasses and put drainage holes in and put in those with perlite and spag moss. they have now started to develop the psudabulbs and the leaves are getting bigger :biggrin :, so when do I need to repot again and with which kind of medium. thanks. your comments would be very much appreciated.