As long as they go in, I don't think it matters when. I dowel each tier and then stack.
I think it all depends on the amount of time you are going to have to do the stacking. If you aren't going to be stressed about getting it stacked it doesn't really matter. If you are going to be stressed for time, I'd go ahead and place the dowels ahead of time.
I like to let the cake settle (preferably overnight if I can) before putting in the dowels. I've found that if I fill and crumb coat, then put the dowels in right away, then when I come in the next morning, the cake has settled and I have to trim another 1/8" to 1/4" more off of the dowels.
I have crumb'd and frosted the same day, but I like to have a few hours between them (crumb in the a.m.; ice in the p.m.) so the cake can settle. I get fewer cracks in the icing and fewer blowouts.
I always appreciate your help.
Thanks.
okay I am probably being really stupid thinking this ( I have had a glass of wine) but what do you mean? Don't you put dowels in as you stack the cake? I wouldn't think that they would do their job if they were put in after the cake was stacked. I don't know. you don't have to explain what you meant to the lush but I was just wondering.
okay I am probably being really stupid thinking this ( I have had a glass of wine) but what do you mean? Don't you put dowels in as you stack the cake? I wouldn't think that they would do their job if they were put in after the cake was stacked. I don't know. you don't have to explain what you meant to the lush but I was just wondering.
I can see how it can be confusing! Here's my take on how I read it:
Do you/we ice the cake, put in the dowels, stack the cake, all within 3-4 minutes? Or .....
Do you/we ice the cake, let it sit overnight to settle, come in the next day, put the dowels in each layer, then stack. (Or sometimes I put the dowels in, transport the cakes unassembled, then stack on site).
I think she was asking how much time between putting in the dowels and stacking the cake.
ah.... now I understand...
I was confused because I have run across people who don't put any dowels in until the cake is full stacked! 
I don't see that working well. Thanks for clearing things up
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