The childcare board is here: www.mumsnet.com/Talk/childcare Parents who employ a nanny and nannies themselves tend to hang out on that part of Mumsnet.
Try not to micro manage, suggest places to go and let your nanny find what works well for them and your son. If you already regularly attend any groups, then have your nanny continue to attend those.
Discuss activity budget and transportation costs. Having a fixed weekly kitty can be useful, so once the money is gone there is no more. You can then adjust the kitty if there are things that need more money.
If your nanny is transporting your son in their car, then suitable car seat is needed and pay for mileage at 45p per mile, which is the maximum current amount before it becomes a taxable benefit. Given fuel cost at the moment, 45p per mile may not cover transport expenses (fuel, wear and tear, insurance, cleaning) but at least it will help towards the cost.
Make sure you have the finances sorted out... payslip and payment to the nanny needs to be with them by the end of the month. If you are using any schemes like Tax Free Childcare, be aware of how long things can take to process.
Write out his current routine as a guide and any things he does when he is tired, hungry etc, so she can learn his ques.
WFH - try to keep out of the way, don't keep popping out of the office to see how they are doing. Be available though, via text message for example, should nanny need to ask you something, or need help. You son needs to have time to get used to someone caring for him, he may accept it very easily, or he may protest.
If you are home at lunchtime and you plan to eat with the nanny and your son, then schedule that with your nanny. It can be a good opportunity for a general catch up chat and can help your son see that you are still there, will still see him, give a cuddle, but not be at his beck and call - nanny is there for his immediate needs. That may help to avoid getting to the stage where he comes and bangs on the office door whenever he wants anything!