1) Open Google Maps

2) Find LA

3) Get directions to New York

4) Choose the route that looks roughly close enough to one you might want to take

5) Look at the distance

6) Determine how far you might want to travel each day (i.e. 80 km/day) ... estimate a bit low just in case something happens to hold you up

7) Divide the total distance by the distance you want to travel

8) Add in a rest day for every 4-8 days of cycling, depending on your preference.

And there you have it.