26 month age gap.
DS3 has just started preschool and DD has just started cruising. Both relevant factors.
Low level stuff - pushing and shoving if baby climbs up whilst he is playing / doing something, lots of physical play (ie older child climbs on younger child), no outright hitting but occasional outbursts.... today DS shoved a wooden toy in the little ones face.
We have tried time outs, sticker charts, we do plenty with him alone, we praise good behaviour. He has settled in amazingly in preschool and I get glowing reports as to how well behaved he is. He is also fine out of the house and if he is with granny / aunty.