Bill,
You probably already know this, but it is worth saying for others that read this post in the future. The first thing you want to ensure is your dryer has forced air. Forced air is needed to cure waterbased inks - whether screen printing or direct-to-garment printing. When the waterbased inks are heated up, the moisture rises into the dryer chamber. The forced air removes the moisture from the chamber to prevent it from failing back on to the garment and preventing the inks from curing properly. You can always call your dryer manufacturer or the dealer you purchased the dryer from to ask if they recommend the dryer model you have for curing waterbased inks.
Regarding the settings, you are looking for a dwell time of approximately 3-4 minutes at 320 degrees F. The difference is time is more associated with how much forced air your dryer has. Some dryers allow you to send through CMYK only and CMYK+W prints without adjusting the belt speed. Others require a longer dwell time for CMYK+W when there is less forced air.
Just so you know (if you are located in the USA and Canada), this information is located in the Owner's Login Website -
https://www.brother-usa.com/IndPrintSewEmb/GarmentPrinters/Owner/Login.aspx. After you login, click on the link for GT-3 Series Reference Guide: Tips & Tricks. Then click the link for Heating Equipment for curing pretreatment and inks.
Best wishes,
Mark