Hi Which Is The Best Time Of The Day To

Hi which is the best time of the day to introduce new food to babies also how do I know if baby likes it or not until now my son 7 months old likes only ragi kanji and banana I tried Apple and rice kanji which he had 4 or 5 spoons and turned his face also he started to show as if he is going to throw out... Shud I still keep trying the food or leave it I gave almost 2 weeks time before I tried the same food again... Also few doctors say to give idli dosa is it okay to give food with salt ? Also for the past one week I have started to give food twice a day and I freel my son is not sleeping well he used in to. Sleep by 10 now he started to sleep only by 1 am only is his related to his evening meal