Domain transfers can take up to 20 days to complete. 10 days for a successful transfer, 20 days if it has failed. You can point the domain to Shopify in the meantime using the correct DNS records.
DNS changes can take up to 48 hours once applied. If you're getting an error that you have conflicting DNS records, then I would suggest contacting Squarespace for further assistance as they are your domain manager until the domain transfers to Shopify.
Trevor | Community Moderator @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog