It really is up to you! I have a hostel of 25 beds and we have been open for 4 years. We have always made the beds because I have the following problems:
matterasses can be stained
not all materasses match
and many Italians do not expect to make their own beds! (we are in Italy)
I have travelled alot and have been in many hostels where you are given the linen at check in and you make your own bed.
I would advise you to evaluate the following from a customer point of view:
The up-side to checking-in and having the bed ready is that you don't have to make it yourself.
The up-side to checking-in and having the linen handed to you is that you are sure it is clean! (Many people think hostels don't wash the linen, crazy!
Anyway, I hope this ha given you some ideas.