A 30 gallon is fine for a group of 4 to 6 yellow labs, but the other fish would of course need to be removed.
For a 30 gallons you do still have some alternatives, Especially from Tanganyika, including shell dwellers, julidochromis transcriptis, Altolamprologus Compressiceps, and Paracyprichromis nigripinnis, not to mention a small group of brichardi. From Malawi Textilis is perfect if you can find it, or you can do a species tank of just Demasoni.
Anyway, there are some options but it will need to pretty much be a species tank (you can get a way with a bristlenose plec, or 3 or 4 synodontis petricola with them.
With cichlids it is a good idea to stock at once, but that also requires a fishless cycle first. Will your place take back your fish and give you credit to use at a later date? This way you can get the cycle done first, and then spend the credit.