Trigger Journey based on DFF value

We have two groups of hires. One group of candidates are hired directly from ORC and moved to HR. The other group are loaded through HSDL. These 2 groups are identified through 2 DFFs in PER_PPS_DF flexfield. The HSDL hires have these 2 DFFs populated while the ORC hires have blank.

We have 2 separate preboarding Journeys for these 2 groups. Currently, when we move someone from ORC to HR, both the preboarding Journeys are getting assigned which is expected because we do not have eligibility profile that separates both the preboarding Journeys. We are looking for writing eligibility profile that checks if the 2 DFFs have some value. If it requires writing Fast formula, please help with sample one.