Actually If you really followed Trump and know him well as you claimed, you should know that he's been all over the place on immigration (as well as many other issues), from pro-amnesty, pro-Dreamers, to his most famous one: touchback immigration, i.e. letting the good immigrants back after they leave. it's not a secret. There is no "I told you so" on this issue. Take a look again on the 3/3/16 GOP candidate debate. Trump said it very clearly.
KELLY: So you abandoning the position on your website
TRUMP: Im changing it, and Im softening the position because we have to have talented people in this country.
You can start to watch it at 35;30, and Trump said it at 36:20.
Link: https://www.youtube.com/watch?v=EOptTq6WYKY