i also have a 15 month old and this will be my second baby, i just believe the key thing to do at this stage is take it one step at a time, if u begin to look at the whole picture from this angle it could be overwhelming and intimidating. at this point my DS still seeks a lot of attention and he still needs a lot of care but i believe when baby comes he'll be almost 2 he'll be much older and able to understand certain things, also able to be independent a lil bit. so don't stress it dont worry over what will happen then just do your best.