JohnOvManc

It depends per person but if you think small regular exposures get people tanned in 1 weeks holiday so it just the same on sunbeds... both are just UV exposure.

If you were lucky for a white guy and were very dark and olive skined anyway 3 times on th sunbeds would have you seeing some noticable colour.
If your skin type 2 then you will take longer, so maybe a month.

Average people are skin type 3 and take a couple of weeks... average usage is 6min on a 200w 60 tube bed EOD...
these people normally up the exposure to 9mins but maybe twice a week to maintain.

Mr average who had a base colour, to get darker they would go 3 times a week at 9 mins.

12mins twice a week starts getting dodgey IMO as the exposure is too intense on such powwerfull beds we have now but people do it.