A time machine is the only item you can have instantly if you'll ever have it in your lifetime. If it takes time, that means you'll never in your life acquire one. Sorry 
Not entirely true. My method for time travel requires that I need an active Multidimensional Energy Radiating Interwarp Triphasic Chronon Linking Universal Beacon to jump back to. Since I didn't establish the first one of these until I was 6 years old, I can't travel back to my early childhood.
Perhaps next time you are jumping back to the 1800s or so, I could give you one of my MERITCLUB transponder units to take back with you?