with Defer

// 1) validate the scheme
var validateD = Promise.defer();

// code to validate scheme
// ..
if (schemeIsValid) {
  validateD.resolve();
} else {
  validateD.reject();
}

// 2 init smth
var initD = Promise.defer();

// some actions to init smth
// ..
initD.resolve();

Promise.all[validateD, initD]).then(function() {
  // everything is ready, let's do the business
});

// get data
var getDataD = Promise.defer();
initD.then(function() {
  // actions to get data
  getDataD.resolve();
});

getData.then(function() {
  // Doing smth with Data
})

withasync

async function validateSchema() {
  await doSomeAsyncSTuff()
  return true;
}

async function init() {
  ..
}

async function getData() {
  ...
}

await* [validateSchema(), init()];
await getData()

without Defer.js

var validate = new Promise(function(sc, er) {
  // code to validate scheme
  // ..
  if (schemeIsValid) {
    sc();
  } else {
    er();
  }
});

var init = new Promise(function(sc, er) {
  // some actions to init smth
  // ..
  sc();
});

Promise.all[validate, init]).then(function() {
  // everything is ready, let's do the business
});

init.then(function() {
  return new Promise(function(sc, er) {
    // actions to get data
    sc();
  }
}).then(function () {
  
});