We generally recommend that the improved design not be modelled until after the base/reference design has been certified to avoid rework in both designs (i.e. any updates required in the reference design during the review process will need to be mirrored in the improved design & recommendations might need to be re-recorded for consistency).
However I would not discourage you from modelling recommendations for practice just because the base design hasn’t been certified yet. Just as long as you’re aware that it may diverge from the reference/base design once it’s certified depending on how much needs to be updated.
So you basically have 3 options:
1. Wait till the base design is certified > clone it > run recommendations
2. Clone the base design as is (prior to certification) > run recommendations on Improved Design A for practice & don’t bother with updating in-line with the certified base design > once base design is certified, clone it again and re-run the recommendations in the new cloned Improved Design B > Submit Improved Design B for certification
3. Clone the base design as is (prior to certification) > run recommendations on cloned Improved Design A > update cloned Design A in-line with certified base design making sure that affected recommendations will need to be re-modelled/re-recorded > Submit Improved Design A for certification.
If you’re inexperienced with the software, I would suggest option 2 as the best option and the least chance of mistakes. You’ll also find that running the recommendations again on the second cloned design will be much faster and you’ll have a tidier result because you’d already know how best to model it. Eventhough it SEEMS like less work, Option 3 just throws up a lot more opportunities for mistakes and messiness due to trying to patch up a bad job. Depending on the udpates, it can also be A LOT MORE WORK to revert the design to a state before the recommendation is modelled.
Another tip is that if you’re trying to record a complicated recommendation, always practice on a cloned design so that you can just jump back to the other design if you stuff things up.
Hope that helps!