According to what I have read, early applications is the right way to go. Check out this link to explain it in more detail and times to do it. http://apps.caes.uga.edu/urbanag/landscape_alert/lace-bugs.cfm
It really depends on where you live. Id wait until it warms a bit. Also do you have pets who chew woody plants? Azaleas are toxic to dogs to begin with. Being a nursery owner in oregon, we dont spray till mid march if there is no snow.
I just looked at the the UGA article and cannot believe they do not warn against systemic insecticides. Remember systemics make every part of the plant poison and there is very good evidence that they are responsible for the bee colony collapse. Here is just a general article, but google systemic insecticides and you will never use them again. http://www.gardensalive.com/article.asp?ai=975
IPM ADVICE FROM UC DAVIS:MANAGEMENT
Tolerate lace bug damage where possible; in most cases, it does not seriously harm plants. Provide proper cultural care so plants are vigorous. No treatment will restore stippled foliage, which remains until pruned off or replaced by new growth. If damage has previously been intolerable, monitor plants early during subsequent seasons. Take action when populations begin to increase and before damage becomes extensive. Biological Control
Natural enemies of lace bugs include assassin bugs, lacewing larvae, lady beetles, jumping spiders, pirate bugs, and predaceous mites. These predators may not appear in sufficient numbers until after lace bugs become abundant; their preservation, however, is an essential part of a long-term integrated pest management program. Growing a variety of species, mulching soil with organic material, and shading plants from afternoon sun can reduce lace bug damage to shrubs and increase natural enemy abundance. If applying pesticides, using only short-persistence materials such as oils and insecticidal soaps will minimize the number of beneficial predators and parasites that are killed. Cultural Control
Grow plants well adapted to conditions at that site. Plants in hot, sunny locations are more likely to be damaged by lace bugs. For example, azaleas grown under partial shade experience less damage by the azalea lace bug in comparison to azaleas that are drought stressed and exposed to bright sun. Provide adequate irrigation and other care to improve plant vigor. Prune out damaged foliage if the discoloring is intolerable and relatively localized. Do not remove more than a small percent of a plant's branches during one season and use good techniques so that pruning does not injure plants, such as by exposing inner branches to sunburn.
AS MOST bug or grass treatment it is more to do with weather temps vs cal date
I can't imagine the situation in which I would use a systemic. I would look at the cultural conditions and see what might be making things so appealing for lace bugs.