I went to do a dummy booking for award travel on Aeroplan yesterday and it says I need 50% of points to get past selection. Getting 50% (150,000) miles is doable via amex. But I don't want to commit the MR points too soon if I don't have to. So my question is can i reserve an award booking for next fall using 50% of the points and accumulate the rest over the next few months, or is it all or none upon the booking (eg aeroplan will have me buy the remaining points at booking)? Sorry if this is confusing.