K.N.
My daughter will be 4 in March. For her, it depends on how bad her congestion is in order to determine what medication/approach is used. Her allergy test showed that we can expect she'll be reactiong to something in the air during all seasons except spring... I try not to medicate her everyday. But if she shows some signs or I know its a key time (like high mold count or high cedar, etc.) or if I am feeling sinus pressure/allergies myself, then I have her children's zyrtec (over the counter) ready in the morning. I buy the name brand, not the generic "just like" kind from the pharmacy or grocery store. I know... people no doubt will say I'm silly; they say the generic stuff is the same.... We had such a roughtime getting her congestion free. She responded well to prescription zyrtec, then they stopped making the prescription kind and only offered the OTC... so I go with the "real" zyrtec name brand. My point is, I've never used the generic 'just like' stuff, so I can't say if it works the same.
If she has a cough from her allergies, then we do a saline neil-med sinus rinse every 1-2 days and combine the zyrtec with a pediatric singular pill (prescription). I really hated the idea of giving her both singualr and zyrted. Boy, I resisted that idea, even though her ENT kept saying that there was some synergy that zyrtec and singular have together... I finally gave her both simultaneously when I was at the end of my rope (she has a series of sinus infections), and WOW! they do work better together than individually. But, again, I only combine both if I hear a cough.
The nasal rinse is key for getting rid of that nasal drip that runs down the back of her throat (which causes my daughter to sinus infections and coughing/bronchiolitis). She hates the nasal rinse, but with enough 'if you cooperate, I have a candy treat', she's agreeable to it.
As for the children's zyrtec, I'm not comfortable giving 1 tsp to a 30 lb 3 year old all at once. It seems like too much, especially since when she was 2 (and 5 lbs lighter) she was only suppose to get a 1/2 tsp. I now give her 3/4 tsp once a day. I tried giving her 1/2 teaspoon in the morning and another 1/2 in the evening, but noticed that she seemed more congested all the time.
I will also add... She doesn't eat cows milk or anything with cows milk dairy due to a food allergy. However, I'm not sure if being off cows milk also helps her experience less seasonal allergy symptoms. I've heard people say that (cows) milk can heighten the symptoms from seasonal allergies. (She's on goat milk, goat yogurt, goat butter, sheep and goat cheeses). I also bought a bread machine and make her a honey bread every week... Mainly because store bought bread has cows milk but also because I read that consuming local honey is suppose to help the individual respond better to pollen allergies (because the honey is made from the local pollen producing flowers and weeds and that helps build up resistence.)
I bathe her every day. I wash her hair every day. Yep, crazy mama here--but I need to get the pollen off her and out of her hair, otherwise she'll get it (pollen) in her bedding and then breathe it in all night too.
She has several lightweight washable jackets. I wash those quite frequently also. Again, I think its key to get the pollen/allergens off the items that she is in contact with often. Same thing for her stuffed animals and lovies... if it leaves the house, its going in the washing machine.
Good luck with the upcoming cedar season!