I'd get megatron from bigbang while you can It seems magmatron too has been delayed. Hasbro pulse was supposed to get him 27th of march now it's 10th of April. So there must be some supply ussues/delays with figures.
I have a (2 actually) €25 voucher for Smyths burning a hole in my pocket since Christmas, Smyths basically never stock Commanders besides a few select stores, and I don't have plans to buy any other Leader Class figures this year. Especially after backing Omega Prime, I'm trying to be smart with my spending (I do have the money to just get him from BigBang, but its more that I like to be smart and budget properly.) so my plan has been to use my voucher on Megatron but its taken a lot longer than expected to drop.
It's odd because the t looks like the UK Smyth's website is getting him soon since the home delivery option has it in stock there, I would have assumed it wouldn't be long after that that it would also be here too
I see he's now listed as due to arrive between April 4th and 11th. Usually once they list the arrival week, it's a pretty safe bet the figure will arrive within that time frame, if not before