The thing that’s important to know is that the rootstock and the scion have influence on fruiting and a lot of other things. Quince though not disease resistant causes pears to fruit very early. I think ohxf333 or ohxf87 would be better choices because they are more compatible and more disease resistant when used with harrow sweet as an example. Oxf333 is the rootstock that produces the smaller tree of those two mentioned. It would likely produce fruit fairly quick. You might also be interested in this thread Pear rootstocks influence on Fruit size and this post Pear tree Fireblight research so you dont have to and Planting out pear rootstock on a large scale