i wouldn't bother with the bands at all.
but guesstimate the sizes of the sections at the scalp
that's how thick the dreads will get eventually wich means they can take 4-6 days to fully dry inside wich is a high mildew risk
over 1 inch thick is risky yes some people have massive dreads 6 or more inches but often they are not very sanitary or healthy (google polish plait)
if you want really fat dreads and don't mind that they are extra hard to care for then by all means carry on...
but if you want to minimize the risk and make them more manageable and easy to care for then it would be best to start over now instead of later
just be aware of what thick dreads that size require
baba fats wrote a post or made a video i forget which about the special care fat dreads require
27 years growing dreadlocks the natural way
My dreads are over 9 feet long