Ther is nothing preventing Ual from recalling now. Most likely they will wait until the vacancies left after the Vacancy bid system wide after SLI.

One thing to think of as a UAL furloughee/cal new hire is if you are on the property that date, that vacancy bid will be your "recall" to UAL.
If you are not on the property yet than the rate of recalls may depend on the "vacancies" unfilled . As more and more new hires on the street come on the CAL property, this will delay the rate at which the UAL guys are recalled.

If you are debating needing to come back this year, I would come back now to the Cal side to be in place for that bid. If you are secure in a grat job, then wait it out.

Eric