Yes, grafting typically shortens the time to bearing but it depends on the species and variety. Grafting also permits the use of a clonal rootstock better adapted to the soil conditions. The combination of these two clones means that an orchard of these trees is more homogeneous and easier to manage commercially.
What i mean in my previous Question was,for example If i use mango seed from grafted mango tree ,seeding will fruit after 6 or 7 years , but if i graft seedling plant can i shorten fruiting time .
Yes, the tree will start to fruit in about 2-3 years. That time will depend on the variety, and the tree management (grafting technique, fertilizer, water, stress, etc.)