An apparatus and downhole method for dynamically establishing in situ an arcuate path of up to 90° or more for a jetting hose or other flexible conduit for forming a lateral bore. The apparatus includes a whipstock comprised of one or more arcuate, telescoping segments which enable the operator to avoid the friction pressure and HHP restrictions of smaller diameter hoses, imposed due to the minimum bend radius restrictions encountered when forming the bend radius solely inside the casing of a wellbore. The apparatus can also be used with a Custom Ported Casing Collar. The hose bending path is established immediately behind the jetting nozzle as the lateral borehole is excavated. Upon retrieval of the flexible conduit and excavation device, the arced extension retracts back into the whipstock body, so as not to impede the whipstock's reorientation and/or depth relocation for forming the next mini-lateral.