So far, everyone I have dealt with was looking to start virtually immediately, or at least within a month or so.
I would never hold a spot for free, because of exactly what you had happen to you. If someone already in care is looking to hold a spot (mat leave, etc) I would charge half the monthly fee, with the allowance that their child could come on a P/T basis if required (10 days per month). For someone looking to hold a spot for a future start date, I would charge a set monthly fee that is non-refundable, and does not get applied to their fees. It is also completely a judgement call for me, as to whether I feel like I can swing it, financially.
I would not even interview for a spot a year in advance. The most I would do is 6 months, and even in that case, I would require a second interview within 2 months of care beginning. I would answer any questions over the phone, etc or via email, because I understand that they want to "plan". But I am not going to put time and energy, and carve out a precious couple hours from my off-time to do that type of interview!