The Scottish Government's Housing Bill includes a change to end the right of social housing tenants to purchase their home with a discount.
It will finally end the policy introduced by Margaret Thatcher in 1980, which led to hundreds of thousands of homes being taken out of the social rented sector.
However, for tenants who still have the right to buy their home, there will be a three-year period before they are barred and the policy is completely ended.
Shelter Scotland said it would like to see it brought down to one year and the right to buy finally stopped sooner.
Rosemary Brotchie, Shelter's Policy Manager, told the Scottish Parliament infrastructure committee: "We don't think the period is necessary."
Andy Young, policy manager of the Scottish Federation of Housing Associations, said: "Three quarters of respondents to the Bill thought it was too long. I agree with Shelter. One year would be appropriate."
David Bookbinder, of the Chartered Institute of Housing in Scotland, and Andy Benson, of the Glasgow and West of Scotland Forum of Housing Associations, also agreed.
Ms Brotchie warned tenants to be on their guard against firms trying to cash in on the right to buy.
She said there are companies who are persuading tenants to buy at the discount, by facilitating mortgages for them, then the home is purchased by the company and let back to the tenant.
She added: "If we allow a longer time period there is potential for these companies to make inroads with more tenants."