Whenever the people vote for it. The SNP (and Greens) were crystal clear in their manifestos in the last elections and people voted for it. In general, people hope that the politicians should do what they said that they would. With Brexit and Tory policies over 10 years, it seems reasonable to have the vote. I would prefer one vote to start the process and final confirmation vote once the exact deal is established. Always a good idea to know exactly what is being offered before taking the deal (total opposite of Brexit) [scot living in Scotland]