Either way it goes Trump is getting impeached either this year or in January 2019. Those are literally the only options that the Republicans have.
They can impeach Trump now and install Pence, which would give the Republicans time to ride out the backlash and recover in time for the 2018 congressional elections. Or the Republicans can fight the impeachment of Trump and then suffer overwhelming election losses in the 2018 congressional races, which would put the Democrats in charge and Trump and probably Pence would definitely get impeached then.
The more that things comes out the more likely it seems that it is the Republicans that want to impeach Trump this year, while the Democrats have more interest in stretching this thing out through the election in 2018, which might allow the independent investigation more time to bloody up the entire Republican party in addition to Trump.