Hey guys--I have been on both sides of this argument.  

Is the Jubilee cycle a 50 year cycle or 49 year cycle?

I believe the answer is clear and lies in Lev 25:3-4:

You shall sow your field six years, and you shall prune your vineyard six years, and shall gather its produce.  (4)  And in the seventh year shall be a sabbath of rest to the land, a sabbath to YHWH. You shall not sow your field, and you shall not prune your vineyard.

If you begin a 49-year cycle with the Jubilee, then because of the prohibiitions in the Jubilee year, you cannot "sow your field six years and prune your vineyard six years" in that first set of years. You would only be able to do that for five years during the first seven years--because the first year would be a Jubilee and the last year would be a land sabbath.   

That doesn't make sense and it is not in keeping with YHWH's symmetry.  He would not make a rule we cannot follow.

The Jubilee cycle is 50 years, not 49.

Blessings,

Mary Ames