According to Forbes Magazine, it shows the enforcement data for CCPA (California Consumer Privacy Act):
Considered to be the most comprehensive in the country, the California Consumer Privacy Act (CCPA) is set to take effect January 1, 2020, with enforcement beginning July 1, 2020. This expansive act is designed to give consumers more control over their personal information and will reach beyond California’s borders.
Currently, the GDPR and CCPA article does not have the enforcement date at the time of posting.
Roblox doesn’t get to decide when they start enforcing this; if a complaint was made by someone under GDPR they’d have to deal with it within a reasonable period or face potential fines from regulators, documented or not Roblox would sooner delete your place if a developer failed to comply. The same will be the case with CCPA when it comes into effect.
GDPR has been law and in effect for around 2 years now. You should have really been ready to enforce it in March 2018 but as Roblox didn’t really provide much guidance it’s not reasonable to expect that.