cPanel 11.39, which is what will eventually become 11.40, is scheduled to go to the EDGE update tier this week, which will be its first exposure to the public. The EDGE tier should not be used on production servers, so I definitely do not recommend using EDGE just for this feature. Unfortunately, I do not have an estimate at this time for when 11.40 will be in public tiers. 11.39 will become 11.40 when it is pushed to the CURRENT tier.
Keep in mind that 11.38 is planned to go to STABLE today, so 11.38 has not made its way down to all update tiers quite yet.