The festival date is according to their lunisolar Bengali calendar as the first of its first month Baishakh. The same day is observed elsewhere as the traditional solar New Year and harvest festival by Hindus and Sikh.
The festival is celebrated with processions fair and family time. The traditional greeting for Bengali New Year is “Shubho Nabobarsho” which is literally “Happy New Year”. The festive Mangal Shobhajatra is organized in Bangladesh.
It is therefore almost always falls on or 14th April every year on the Gregorian calendar, and is known by other name such as Vaisakhi in Central and North Indian, Vishu in Kerala and Puthandu in Tamil Nadu.
Bangladeshi eats festive food on Pohela boishakh. These include panta bhat (watered rice) ilish vaja (fried hilsa fish), and various special bharta (pastes). Begali families clean their house and decorate them with alpana (rangoli).
Bengali people prefer to eat during breakfast i.e. Luchi and alur torkari, Phulko luchi. And for lunch Mutton biryani, Peas pilaf, Muri ghonto and veg dishes are Laal shaak bhaja, Shukto. Snacks, Kochi nimki, Onion pakora, Vegetable chop, Egg roll, Chili garlic dip.
Whole tilapia is a whole fish. No Bengali celebration is complete without this dish. It can be cooked on stove or in oven. It very tasty and felicitous that people love to eat, common but simple Bengali spices that are used to cook every day fish, infuse this whole tilapia.
A Bengali New Year is incomplete without the taste of puri/poori which is usually served during breakfast. These sinful deep fried unleavened bread which is loved and made in every Bengali house.

Source:[http://indiafoodnetwork.in/food-stories/ring-bengali-new-year-mumbai/]