Once they have ensured any firmware update does not clash or conflict with their Network and devices they will release it on a staggered rollout for Branded Handsets.
Those on Un Branded phones occasionally get the update faster.
Keep checking your settings in your phone.
Check blogs etc to ensure others with your device have not run into bugs etc before committing your device to the new OS.
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.