After a nine month grounding it was indeed like riding a bike. Yes, i was required to complete three simulator sessions and a short LIFUS phase (line flying under supervision), but that was more about SOPs and getting up to speed with those than flying itself. So pretty similar to what the others have said here.
What i would say though, be aware that you are just a tad slower than normal, so take your time and be thorough in what you do. At least that is my observation. However, aircraft that have been basically in maintenance for the last few months, that could be interesting.
I don't care how i look on the first back to work SIM, that is training, and why would i ever consider to train for the training on my own dime?