I am looking for suggestions on how to track down my immigrant ancestors from Scotland. The proliferation of (seemingly) random ship rosters is bewildering at best. Specifically, I'm looking for William May, born 1816 in Lonmay, Aberdeenshire. He ended up in Lanark County, Ontario but the timing is unknown. It would be somewhere between 1820 and 1845 is my guess, based on his presence on census documents in 1851 with a family that did NOT immigrate with him. He married Agnes Cameron in Ontario sometime after his arrival.

Any good suggestions on how to find out when he arrived?? Thanks!