Note- A US listing would also allow ALDA to do a PP to US residents.....
Some info about time frame:

"The Form 20-F filing (and the related applications with Nasdaq or an exchange) is a much more significant event. It requires the company to make a commitment to designate a team consisting of its chief financial officer or controller, outside accountant, and a mid-level corporate official to work with U.S. securities counsel to prepare, review, and revise the filing and related exhibits. The filing is lengthy - 80 pages (not including financial statements) is not unusual. The company should expect at least a month's preparation prior to filing and expect at least 30 days to elapse after filing before the SEC issues its first letter of comments on its initial review of the filing. The total process could take at least 120 days. In order to speed up the process, the company should ensure that its designated personnel are delegated to the Form 20-F full-time both prior to filing and then again following receipt of the SEC's letter of comments".