Starting sequence in PFC AND SMPS Design
When you associate a PFC with a downstream circuitry, you have to think about the start-up sequence depending on how the downstream converter operates:

if it is a universal-mains design, e.g. a flyback converter accepting to operate down to 85 V rms by design, then it can start-up first and once its auxiliary power is alive, it powers the PFC circuit. This is a very common practice.

there are converters that do not lend themselves well to a universal input range. Forward and LLCs are among these converters and the PFC must start first before cranking the second converter. A small logic glue is thus necessary to ensure this synchronization between both converters.


I have often seen both control sections (PFC and forward) powered by the same \$V_{cc}\$ rail but the forward PWM was kept silent until the PFC output voltage was stabilized (PFCs can be prone to start-up overshoots considering the low bandwidth). A simple timer started after the PFC is powered is usually good enough or, if available, the brown-out input of the PWM controller selected for the forward can also be used for that purpose.
A final note, the MC33262 is a venerable PFC controller launched after the 33261 during the MOT era. If it works well, it no longer meets all safety criteria required for new designs. Beside, I would recommend to implement a charge-pump around the auxiliary winding rather than a peak rectification as shown in the 262 data-sheet. This voltage is highly variable with the mains while you can keep it stable in an easier way with a charge-pump. See the below circuit excerpted from here:

disclaimer: beside writing articles and publishing books, I also work for a semi company :-)