Wait till they reach 5-10% thats when the problem starts and then see what happens,Every non-muslim country which had muslim population over 5-10% has fights and problems.
over 10=20% they want sharia rule imposed and special courts for them.
India has been defending against islamic hordes since past 1000 years.Take our word for it, they are all rosy in the beginning, the brotherhood, the peace, iftar blah blah blah India too first gave permission to the arab muslims traders to build their places of worship in kerala,later when they grew in number they attacked the same king who let them practise and trade in his kingdom,
As some priest said" Islam is growing here and there are many conversions with marriages etc."
That is where your problem will start.It is a slow poison you wont even know when they become majority and you become minority in your own country.