Approvals for Spark AR camera effects / filters, can take up to ten business days for Instagram depending on the type of effect.
Filters for Facebook tend to be quicker and take less than a week. Its is possible that Facebook will reject a filter or effect submitted for approval. They have guidelines as to their reasons for this and to provide insight as to best practices.
Most Spark AR creators (on Blend Market) will have a lot of experience when it comes the guidelines and how to navigate them and they will take the lead on ensuring Facebook's creative, policy, and technical compliance terms are met to minimise the risk of the filter being rejected.