President Trump is going to be a very busy man on day one..... and far beyond.
You say that because you are poorly informed. Trump, like Obama and George Bush, will have a policy that is determined by the money that Congress appropriates.
The US has a policy of quickly returning to Mexico, Mexican illegals caught in the border zone, because Mexico accepts them. And most illegal Mexicans consent to this because the apprehension doesn't go on their record.
But, Mexico won't accept illegals from other countries(Other than Mexican-OTMs), say El Salvador or China.
These OTMs have to be returned to their home country and they have to be given a hearing before they can be returned, and the home country must accept them before they can be returned.
Which means, you have to have detention facilities, officers, judges, courtrooms, and everything else needed to hold them until they can be sent back.
That takes money.
This was a very big issue back in 2005, it was called "catch and release". Because they couldn't be given a hearing at the time they were apprehended, the Border Patrol would give the OTM a written "order to appear" for his hearing, then released, and wouldn't return for his hearing. All the OTMs knew this and would turn themselves into the first officer they could find after they crossed the border
So Bush finally got Congress to appropriate more money so he could deal with the catch and release of the OTMs. But Congress said that women and children OTMs can't be held in a jail, they have to be detained in a "home like setting", which means they get catch and release.
So today, the women and children OTMs look for the first officer they can find after they cross the border.
This is like any and all problems, it can be solved with more money, but Congress has to appropriate the money. Same way with Sanctuary Cities: get Congress to appropriate more money instead of pushing it off on local law enforcement and the local taxpayers.