Hi, although the question is related to MDD, i thought it wouldn't harm pulling a reference from MDR.
According to MDR Article 2 definition 28, IVDR Article 2 definition 21,
‘Placing on the market’ means the first making available of a device, other than an investigational device, on the EU market.
Then...
According to MDR Article 2(27).
‘Making available on the market’ means any supply of a device, other than an investigational device, for distribution, consumption or use on the Union market in the course of a commercial activity, whether in return for payment or free of charge.
So, to answer your question, whether it is cleared from custom or stored in distributor warehouse, as long as it enters in European Market in course of a commercial activity (Free of charge or in return of payment), it is considered placing on the market. Only exception is device for investigation purpose.
Hope this helps.