Mo. Rev. Stat. § 302.308

The director in warning an operator of his conviction record or in issuing an order suspending or revoking his driving privileges shall not convert to points or use as a basis of suspension or revocation any conviction which occurred more than six months prior to the effective date of sections 302.302 to 302.309, provided, however, that such accumulation of points resulting from convictions prior to the effective date of sections 302.302 to 302.309, shall not cause a suspension or revocation of any driving privileges, not suspendable or revocable under the law existing prior to such effective date *, until there has been further violation or violations under the provisions of sections 302.302 to 302.309.